Activation of Stable and Recyclable Phenylpropiolate Glycoside (PPG) Donors by Iron Catalysis

Abstract

The glycosylation reaction is one of the important aspects of carbohydrate chemistry, where two different units are frequently linked through C–O bonds. In the pursuit of advancing this field, the design and development of sustainable catalytic methods for O-glycosylation, which can provide an alternate and effective tool to traditional protocols involving stoichiometric promoters and classical donors, are considered as highly challenging, yet important facets of glycochemistry. Herein, we report a simple and efficient Fe(III)-catalyzed method for O-glycosylation through the activation of bifunctional phenylpropiolate glycoside (PPG) donors. This mild and effective method involves the use of the inexpensive and less toxic FeCl₃ as catalyst and easily synthesizable, benchtop-stable glycosyl ester-based PPG donors, which react with various sugar as well as non-sugar-based acceptors to deliver the corresponding O-glycosides in good yields with moderate anomeric selectivity, along with regeneration of easily separable phenylpropiolic acid. Importantly, d-mannose and l-rhamnose-based PPG donors afforded the corresponding O-glycosides in high α-anomeric selectivity. The reaction conditions were further explored for the synthesis of trisaccharides.

Carbohydrates and their derivatives play an indispensable role across the field of science, from providing the source of energy to controlling several important biological events.[1] Apart from this, carbohydrates and their derivatives serve as key synthetic building blocks to address the issues related to glycobiology and medicinal chemistry.[2] In general, two basic carbohydrate units are linked mostly through C–O bonds, and the process of this bond formation is called O-glycosylation.[3] Nature in general makes these bonds using the active glycosyl phosphate based donor in the presence of glycosyltransferase enzymes. Even though these protocols have their own merits in terms of anomeric selectivity, the major issue lies with the stability and cost of the glycosyl donors, which eventually make these processes unsuitable for large-scale synthesis.[4] Hence, the development of sustainable catalytic chemical methods for O-glycosylation using stable and cost-effective donors/promoters is considered as one of the primary areas of research in glycochemistry and, consequently, considerable attention has been paid to this field by chemists around the world.[5]

Thus, chemical synthesis becomes a valuable and alternative tool for accessing the important and critically defined natural and unnatural oligosaccharides in pure form as well as in large-scale synthesis. In principle, the overall outcome of chemical glycosylation reactions, including the yields and anomeric selectivity of the desired products, depends on the nature of the glycosyl donors as well as the promoters in the reaction medium.[6] Therefore, several well-documented glycosyl donors have been designed and developed in the last 40 years such as glycosyl halides, thioglycosides, glycosylimidates and thioimidates, sulfoxides, glycosyl phosphates, phosphites, 1-hydroxy sugars, and 1,2-anhydro sugars and have been extensively employed for the synthesis of complex oligosaccharides and glycoconjugates.[7] In the recent past, bifunctional classes of donors have become the first choice of glycosyl donors for chemical glycosylation reactions, owing to their ease of synthesis, cost, and stability.[8] The bifunctional classes of donors mostly possess an alkyne bond along with an ester, amide, or carbonate functionality, which in general gets activated by Au(I/III)/Ag(I) salts or Hg(II), with the generation of one equivalent of byproducts (Scheme [1]).[9] To sort out the problem associated with the formation of lipophilic byproducts, we have recently reported PPG-based donors, which are easily obtained by the coupling of lactols and commercially available phenylpropiolic acid, affording the desired glycosylated products in good yields in the presence of AuCl₃ (10 mol%), a soft Lewis acid with π-acidic character, with the regeneration of hydrophilic and easily separable phenylpropiolic acid (Scheme [1e]).[10] It should be noted that the alkynyl ester-based donors commonly used either expensive noble metals such as Au(I), Au(III), or Ag(I) or toxic metal salts such as Hg(II) as the promoters for the glycosylation reaction; this is not very sustainable in terms of cost and, hence, is unsuitable for large- or industrial-scale synthesis. In contrast, the utilization of more earth-abundant, less toxic, and cost-effective 3d-metal salts as optimal catalysts for the activation of bifunctional donors has been less explored in carbohydrate chemistry.[11]

Therefore, with sustainability in synthetic carbohydrate chemistry as an important consideration, we decided to focus our attention towards the use of inexpensive and more earth-abundant transition-metal-based promoters for the activation of easily synthesizable PPG donors for the O-glycoside bond formation. Iron is one of the most accessible, affordable transition metals and, consequently, a variety of iron-based salts have been utilized for organic transformation reactions including C–H activation/functionalization.[12] Moreover, Fe(II) or Fe(III) salts have also been employed as desired catalysts in glycosylation, through the activation of numerous glycosyl donors, including anomeric acetates, halides, and imidates.[11a] [13] Very recently, Yao and coworkers reported a method for the direct synthesis of 2-deoxy glycosides from 3,4-O-carbonate glycals by using an Fe(III) salt as the optimal catalyst.[14] On the basis of this prior understanding and the importance of Fe-based salts as a desired catalyst, we anticipated that the carbonyl group and alkyne motif of PPG donors will form complex A with the Fe(III) salt, and that this will eventually trigger the cascade process involving departure of the ester group to generate oxocarbenium species B; this would be followed by a nucleophilic attack to form the desired glycoside products 11 (Scheme [1g]). To the best of our knowledge till date, the use of an Fe(III) salt as the promoter for the activation of alkyne-containing ester-based donors has not been reported. In continuation of our interest in the development of novel glycosylation protocols,[10] [15] herein we report an Fe(III)-catalyzed chemical glycosylation protocol proceeding via the activation of phenylpropiolate glycoside donors, which strike a balance between shelf stability and being a sustainable promoter.

We first prepared a series of phenylpropiolate-based glycosyl donors 9a–g by coupling of various glycosyl hemiacetals and phenylpropiolic acid by the established literature procedures[10] (Figure [1]). The α/β ratios of the prepared compounds were determined by detailed ¹H NMR analysis.

After that, we began our study by performing the reaction with 2,3,4,6-tetra-O-benzyl-α/β-phenylpropiolate glycoside (9a) as the glycosyl donor and isopropanol as the glycosyl acceptor in the presence of anhydrous FeCl₃ (10.0 mol%) as catalyst in anhydrous DCM at room temperature (25 °C) for 24 h (Table [1], entry 1). However, no desired O-glycosylated product was formed under these conditions and the starting material remained intact (TLC analysis) and was recovered through column chromatography. Switching the reaction temperature from 25 °C to 45 °C gave the desired product 11a in an optimum yield of 52% with moderate anomeric selectivity (entry 2). The anomeric ratio of the corresponding glycoside was determined through detailed NMR analysis. The nature of the solvent plays a pivotal role in glycosylation reactions,[16] and therefore we screened various solvents, including MeCN, Et₂O, THF, and CHCl₃ to improve the overall yield of the glycosylation reaction (entries 3–6); the results indicated that DCM is the optimal solvent for the reaction. Afterwards, different iron salts such as Fe(OTf)₃, FeCl₂, and Fe(acac)₃ were also tested as promoter for the activation of the PPG donor and, among them, Fe(OTf)₃ provided the corresponding glycoside 11a in 43% yield (entry 7), whereas FeCl₂ and Fe(acac)₃ failed to generate the desired product (entries 8 and 9). It is worth noting that, when the reaction was performed in the presence of hydrated FeCl₃∙6H₂O salt as a catalyst, the corresponding glycoside (11a) was isolated in inferior yield (30%) along with hydrolyzed hemiacetal product (entry 10). Other reaction parameters such as concentration and stoichiometry also have an impact on the efficiency of the glycosylation reaction and, therefore, several other reactions were performed. For example, when the reaction was performed with 2 equivalents of acceptor, it resulted in an improved yield and the desired glycoside 11a was obtained in 60% yield (entry 11). Moreover, an increase in the solvent concentration from 0.05 M to 0.1 M led to a significant increase in the product yield (75%, entry 12). However, a decrease in catalyst loading from 10 mol% to 5 mol% led to a reduced yield of 53% and recovery of the rest of the starting material (entry 13).

Table 1 Optimization of Reaction Conditions^a

Entry	Catalyst	Temp (°C)	Solvent	Time (h)	Yield (%)b	Ratio α/β
1	FeCl3	r.t.	DCM	24	n.r.	-
2	FeCl3	45	DCM	24	52	1.3:1
3	FeCl3	45	MeCN	24	n.r.	-
4	FeCl3	45	Et2O	24	n.r.	-
5	FeCl3	45	THF	24	n.r.	-
6	FeCl3	45	CHCl3	24	n.r.	-
7	Fe(OTf)3	45	DCM	24	43	1.1:1
8	FeCl2	45	DCM	24	trace	-
9	Fe(acac)3	45	DCM	24	n.r.	-
10	FeCl3·6H2O	45	DCM	12	30	1.2:1
11c	FeCl3	45	DCM	24	60	1.2:1
12d	FeCl3	45	DCM	12	75	1.4:1
13e	FeCl3	45	DCM	24	53	1.3:1
14f	FeCl3	45	DCM	12	61	1.3:1
15g	HCl	45	DCM	24	n.r.	-

^a Reaction conditions: 9a (0.10 mol), i-PrOH (0.12 mol), catalyst (10 mol%), 4 Å MS, solvent (0.05 M).

^b Isolated yield of product after purification by column chromatography; n.r. = no reaction.

^c i-PrOH (2.0 equiv) was used.

^d i-PrOH (1.2 equiv) and DCM (0.1 M) were used.

^e FeCl₃ (5 mol%) was used.

^f i-PrOH (2.0 equiv) and DCM (0.1 M) were used.

^g A 4.0 M solution of HCl in dioxane (10 mol%) was used.

Notably, an increase in the loading of the acceptor from 1.2 to 2 equivalents in 0.1 M DCM did not make any significant contribution in terms of yield, and the desired product was obtained in only 61% yield (Table [1], entry 14). Since HCl is generated in situ from the FeCl₃ salt during the course of the reaction, which might play a crucial role in the activation of the alkynyl ester-based PPG donor, the reaction was carried out with HCl (10 mol%) in dioxane as the catalyst (entry 15). However, no desired product was formed and the donor remained stable and could be recovered by column chromatography. The outcome of the result clearly ruled out any role of HCl in this glycosylation process. After detailed optimization of different reaction parameters, the reaction conditions mentioned in entry 12 were selected as the standard conditions for further exploration.

With the optimized reaction conditions in hand, we further explored the scope of the FeCl₃-catalyzed glycosylation reaction with various carbohydrate- as well as non-carbohydrate-based acceptors (Figure [2]); the results are tabulated in Scheme [2]. The Fe(III)-catalyzed glycosylation of donor 9a with a series of monosaccharide-derived acceptors were performed. For instance, carbohydrate acceptors A–C containing a primary hydroxyl group (C6-OH) gave the corresponding disaccharides 11b–d in good yields (up to 71%) with moderate anomeric selectivity. Similarly, differentially protected, either armed or disarmed 6-hydroxy thioglycosides D and E reacted well under the reported conditions, giving the desired products 11e,f in good yields without activation of the thioglycoside donor under the developed reaction conditions. Likewise, sterically more challenging carbohydrate-based acceptors containing secondary hydroxyl groups (C4-/C3-/C2-OH) were also tested under the FeCl₃-catalyzed conditions. For example, the C4-hydroxy-containing sugar acceptor F produced disaccharide 11g (71%). Sterically hindered sugar acceptors, particularly C3- and C2-hydroxy-containing G and H, also delivered the corresponding glycosides 11h,i in 70% and 44% yield, respectively. Interestingly, high anomeric selectivity was observed in the case of the C3-hydroxy sugar acceptor G. A wide variety of non-sugar alcohols also participated smoothly in the glycosylation reaction, regardless of being bulky, like adamantanol, (+)-menthol, (–)-menthol, and cholesterol, and the corresponding products 11j–m were obtained in good to excellent yields.

To check the compatibility of this catalytic system with other commonly used protecting groups in carbohydrate chemistry, acid-sensitive acetal and silyl (TBDPS) based PPG donors 9b and 9c were also used in the reaction (Scheme [2]). The glycosylation reactions of donors 9b and 9c with various carbohydrate- as well as non-carbohydrate-based acceptors proceeded well and gave the desired products 12a–f and 13a–c, respectively, in moderate to good yields and with marginally high α-anomeric selectivity, without affecting the protecting groups.

After achieving success with the glucopyranosyl PPG donors, a panel of diverse glycosyl donors including d-mannose, d-galactose, and l-rhamnose PPGs (9d–f) were explored in the Fe(III)-catalyzed glycosylation with different glycosyl acceptors; the results are tabulated in Figure [3]. To our delight, all the donors reacted smoothly with sugar as well as non-sugar acceptors under the Fe(III)-catalyzed conditions to afford the corresponding products in moderate to good yields. Noteworthy, the mannosyl donor gave the corresponding disaccharides 14a–j in exclusively α-anomeric selectivity. Moreover, the results with d-galactopyranosyl PPGs, forming 15a–g were also productive in terms of yields as well as selectivity (Figure [3]). Remarkably, when the reaction was performed with l-rhamnosyl PPG donor 9f with glucose and galactose-based acceptors (C6-OH), the corresponding glycosides 16a,b were isolated in good yields with exclusive α-selectivity (Figure [3]).

In carbohydrate chemistry, the orthogonal protecting strategy is an important aspect, particularly for the synthesis of complex oligosaccharides.[7f] [17] Therefore, we became interested in showcasing the orthogonality character of the reported catalytic system, anticipating that the FeCl₃ salt would not interfere with the activation of the thioglycoside donor or that the PPG donor will be stable under NIS/TMSOTf conditions. Therefore, stepwise glycosylation reactions for the synthesis of trisaccharides were carried out (Scheme [3]). First, d-galactose PPG donor 9e reacted with the C6-OH-containing thioglycoside acceptor E in the presence of FeCl₃ (10.0 mol%), furnishing the desired disaccharide 15d, which was subsequently subjected to a reaction with a C6-OH acceptor under NIS/TMSOTf conditions to afford trisaccharide 17 in 52% yield. Second, glycosylation of thioglycoside donor 18 with acceptor 19 in the presence of NIS/TMSOTf at 0 °C took place smoothly, giving the corresponding disaccharide PPG donor 20 as product, without affecting the ester moiety (Scheme [3]). Furthermore, donor 20 was subjected to the Fe(III)-catalyzed glycosylation conditions with a C6-OH glucose acceptor to give trisaccharide 21. Indeed, these results clearly illustrate the orthogonal character of the developed catalytic conditions as well as the PPG donors.

To understand the mechanistic aspects of the glycosylation reactions, several control experiments were carried out. Other Lewis acids were also tested to illustrate the crucial role of FeCl₃ in coordinating with the bifunctional donor (Scheme [4a]). For instance, the glycosylation reaction was carried out with other Lewis acids such as AlCl₃, MnCl₂·4H₂O, and CoCl₂ under similar conditions. Nonetheless, the formation of the desired product was not observed (by TLC analysis), even after 24 hours of reaction time (Scheme [4a]). These results clearly indicate that FeCl₃ not only acts as optimal Lewis acid under these reaction conditions, but also activates the bifunctional PPG donor via coordination of the triple bond. Furthermore, when the glycosylation reaction was performed with 2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranosyl 3-phenylpropionate (9g) as a donor under similar conditions, the desired glycoside 11a was obtained, albeit in lower yield (14%) and the rest of the starting material was recovered (Scheme [4b]). This result demonstrates the importance of the alkyne group adjacent to the ester moiety in the PPG donor, which essentially helps in coordination with the dual acidic character (Lewis acid or π-acid) of the Fe(III) salt.

To demonstrate the synthetic practicality of the developed glycosylation protocol, a scale-up reaction was performed under the optimized conditions, providing the desired product 11b in 65% yield (Scheme [4c]). Considering that hydrophilic phenylpropiolic acid is regenerated during the glycosylation reaction, we became interested in determining the reusability of phenylpropiolic acid. The acidification of the aqueous phase with 1 M aq HCl and further extraction with DCM regenerated phenylpropiolic acid (71%; Scheme [4c]). Subsequently, the regenerated phenylpropiolic acid was coupled with glycosyl hemiacetal to produce the corresponding PPG donor 9a in 82% yield (Scheme [4c]).

In conclusion, we have successfully developed an efficient and simple method for O-glycosylation via Fe(III)-catalyzed activation of stable and recyclable alkyne-containing glycosyl ester (PPG) donors. This approach provides a benign and sustainable catalyst for the activation of PPG donors, which had been typically achieved by using either noble metal (Au) or toxic metal (Hg) salts. The developed protocol shows good functional group tolerance and worked well with a broad range of sugar- as well as non-sugar-based acceptors to afford the products in good to excellent yields. Further, we have demonstrated the potential utility of the developed protocol for the synthesis of trisaccharides. The use of FeCl₃ salt as a promoter enhances the sustainability of the method and makes it an attractive option for large-scale synthesis of complex glycoconjugates. We anticipate that the Fe(III)-catalyzed glycosylation protocol will find wide application in the synthesis of various intricate glycoconjugates.

All chemicals were purchased as reagent grade and used without further purification unless otherwise mentioned. Solvents were purified by standard procedures. All reactions were carried out under a nitrogen atmosphere with freshly distilled solvents unless otherwise mentioned. MS (4 Å) were flame-dried before use. Reactions were monitored by analytical TLC (60 F₂₅₄ silica gel, precoated on aluminum plates). TLC plates were visualized by spraying with 10% H₂SO₄ in MeOH and heating until spots appeared or under UV light (254 nm). Column chromatography was performed using silica gel (100–200 mesh). NMR spectra were recorded at 400 and 100 MHz (¹H NMR) and 500 and 125 MHz (¹³C NMR). Chemical shifts (δ) are reported in ppm relative to TMS or the residual solvent signals (¹H NMR: CDCl₃: δ = 7.26; ¹³C NMR: CDCl₃: δ = 77.00, CD₂Cl₂: δ = 54.00). HRMS spectra were recorded on an ESI-MS spectrometer (Q-TOF, positive ion). Literature procedures[18] [19] [20] [21] [22] [23] [24] [25] [26] [27] were followed for the preparation of the carbohydrate-based glycosyl acceptors 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose (A), methyl 2,3,4-tri-O-benzyl-α-d-glucopyranoside (B), methyl 2,3,4-tri-O-benzyl-α-d-mannopyranoside (C), phenyl 2,3,4-tri-O-benzyl-β-d-thioglucopyranoside (D), phenyl 2,3,4-tri-O-benzoyl-β-d-thioglucopyranoside (E), methyl 2,3,6-tri-O-benzyl-α-d-glucopyranoside (F), methyl 2-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (G), and methyl 3-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (H). Non-carbohydrate-based alcohols I–O were used as commercially available.

Glycosyl Donors 9a–g; General Procedure GP-1

An oven-dried round-bottom flask was charged with the appropriate glycosyl hemiacetal (1.0 mmol) and the acid coupling partner (phenylpropiolic acid for 9a–f; 1.5 mmol) in anhydrous DCM (5 mL); the mixture was stirred at 0 °C for 30 min. A mixture of DCC (1.5 mmol) and DMAP (0.2 mmol) in anhydrous DCM (5 mL) was added to the reaction mixture at 0 °C, and the mixture was brought to r.t. The mixture was stirred at r.t. until completion of the reaction, as monitored by TLC. Then the mixture was diluted with DCM and filtered through a pad of Celite. The filtrate was concentrated in vacuo and purified by column chromatography (silica gel, EtOAc/hexanes) to afford the corresponding glycosyl donor 9.

2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl Phenylpropiolate (9a)

Compound 9a was obtained from the reaction between 2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranose (540 mg, 1.0 mmol, 1.0 equiv) and phenylpropiolic acid (219 mg, 1.5 mmol, 1.5 equiv) by following GP-1.

Yield: 574 mg (86%, α/β = 2:1); pale-yellow liquid; R_f = 0.4 (EtOAc/ hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.65–7.59 (m, 3 H), 7.51–7.27 (m, 31 H), 7.14 (dd, J = 6.5, 3.0 Hz, 3 H), 6.44 (d, J = 3.5 Hz, 1 H), 5.73 (d, J = 7.8 Hz, 0.5 H), 5.01 (d, J = 10.9 Hz, 1 H), 4.93 (d, J = 10.9 Hz, 0.5 H), 4.90–4.80 (m, 4 H), 4.78 (d, J = 8.2 Hz, 0.4 H), 4.72 (d, J = 10.7 Hz, 1 H), 4.68 (d, J = 5.2 Hz, 0.4 H), 4.66–4.60 (m, 1 H), 4.55 (d, J = 10.7 Hz, 0.6 H), 4.52 (d, J = 7.1 Hz, 1.4 H), 4.50–4.47 (m, 1 H), 4.10–4.03 (m, 1 H), 4.01–3.97 (d, J = 10.0 Hz, 1 H), 3.83–3.72 (m, 5 H), 3.70–3.60 (m, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 152.5, 152.4, 138.6, 138.3, 137.1, 137.7, 137.5, 133.2, 131.0, 130.9, 128.7, 128.6, 128.5, 128.4, 128.3, 128.1, 128.0, 127.9, 127.8, 127.7, 119.4, 119.3, 95.1, 91.6, 88.4, 87.9, 84.7, 81.6, 80.8, 80.3, 78.7, 75.8, 75.4, 75.2, 75.1, 73.6, 73.5, 73.1, 68.0, 67.9.

2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranosyl Phenylpropiolate (9b)

Compound 9b was obtained from the reaction between 2,3,4-tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranose (554.6 mg, 1.0 mmol, 1.0 equiv) and phenylpropiolic acid (219 mg, 1.5 mmol, 1.5 equiv) by following GP-1.

Yield: 613 mg (82%, α/β = 2:1); pale-yellow liquid; R_f = 0.40 (EtOAc­/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.68–7.50 (m, 9 H), 7.46–7.27 (m, 19 H), 7.25–7.10 (m, 11 H), 6.42 (d, J = 3.5 Hz, 0.5 H), 5.66 (d, J = 7.8 Hz, 1 H), 4.95–4.61 (m, 9 H), 4.04–3.80 (m, 6 H), 3.73–3.58 (m, 3 H), 3.42 (d, J = 9.6 Hz, 1 H), 1.00 (s, 14 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.5, 152.3, 138.5, 138.2, 138.0, 137.9, 137.6, 135.9, 135.8, 135.6, 133.5, 133.2, 133.1, 132.8, 131.0, 130.8, 129.6, 128.7, 128.6, 128.5, 128.2, 128.1, 127.9, 127.8, 127.7, 127.6, 127.5, 119.4, 119.3, 95.3, 91.6, 88.2, 87.6, 84.6, 81.6, 81.1, 80.3, 80.1, 79.3, 76.4, , 76.0, 75.4, 75.2, 74.2, 73.5, 62.0, 26.8, 19.3.

4,6-O-Benzylidene-2,3-di-O-benzyl α/β-d-glucopyranosyl Phenylpropiolate (9c)

Compound 9c was obtained from the reaction between 4,6-O-benzylidene-2,3-di-O-benzyl α/β-d-glucopyranose (500 mg, 1.11 mmol) and phenylpropiolic acid (557 mg, 1.6 mmol, 1.5 equiv) by following GP-1.

Yield: 534.0 mg (80%, α only); pale-yellow liquid; R_f = 0.3 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.66–7.60 (m, 4 H), 7.52–7.46 (m, 6 H), 7.42–7.37 (m, 12 H), 7.36–7.29 (m, 17 H), 6.35 (d, J = 3.8 Hz, 0.77 H), 5.83 (d, J = 7.9 Hz, 1 H), 5.59 (s, 1.8 H), 4.96 (dd, J = 11.3, 6.7 Hz, 2 H), 4.88–4.80 (m, 4 H), 4.77 (d, J = 4.2 Hz, 1 H), 4.40 (dd, J = 10.4, 5.0 Hz, 1 H), 4.34 (dd, J = 10.4, 4.9 Hz, 1 H), 4.12 (d, J = 9.3 Hz, 1 H), 4.08–4.03 (m, 1 H), 3.90–3.86 (m, J = 8.9 Hz), 3.80–3.67 (m, 6 H), 3.63–3.58 (m, 1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.5, 152.0, 138.5, 138.1, 137.6, 137.4, 137.1, 137.0, 133.2, 133.1, 130.9, 129.0, 128.9, 128.6, 128.6, 128.5, 128.4, 128.4, 128.3, 128.3, 128.2, 128.15, 128.1, 128.1, 127.9, 127.7, 125.1, 119.3, 119.1, 101.3, 101.2, 95.0, 91.8, 89.1, 88.7, 88.27, 88.5, 81.3, 81.1, 80.1, 80.1, 79.8, 78.3, 77.8, 75.4, 75.1, 73.9, 68.6, 68.4, 66.7, 65.0.

HRMS (ESI/Q-TOF): m/z [M + H]⁺ calcd for C₃₆H₃₂O₆: 577.2226; found: 577.2223.

2,3,4,6-Tetra-O-benzyl-α/β-d-mannopyranosyl Phenylpropiolate (9d)

Compound 9d was obtained from the reaction between 2,3,4,6-tetra-O-benzyl-α/β-d-mannopyranose (557 mg, 1.03 mmol, 1.0 equiv) and phenylpropiolic acid (225 mg, 1.55 mmol, 1.5 equiv) by following GP-1.

Yield: 534.0 mg (80%, α/β = 1.8:1); pale-yellow liquid; R_f = 0.37 (EtOAc­/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.60–7.56 (m, 2 H), 7.50–7.46 (m, 1 H), 7.43–7.27 (m, 21 H), 7.20–7.16 (m, 2 H), 6.33 (d, J = 2.1 Hz, 1 H), 4.90 (d, J = 10.5 Hz, 1 H), 4.78 (q, J = 12.4 Hz, 2 H), 4.70 (d, J = 12.1 Hz, 1 H), 4.65–4.59 (m, 2 H), 4.58–4.56 (m, 1 H), 4.54 (d, J = 2.0 Hz, 1 H), 4.14 (t, J = 9.7 Hz, 1 H), 3.99–3.94 (m, 2 H), 3.86–3.81 (m, 2 H), 3.75 (dd, J = 11.1, 1.8 Hz, 1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.0, 138.1, 137.6, 133.1, 131.0, 128.7, 128.6, 128.5, 128.4, 128.3, 128.1, 129.0, 129.1, 128.0, 127.9, 127.8, 127.7, 127.5, 119.1, 93.2, 87.7, 80.0, 79.1, 75.3, 74.6, 74.0, 73.5, 73.0, 72.5, 72.2, 68.6.

2,3,4,6-Tetra-O-benzyl-α/β-d-galactopyranosyl Phenylpropiolate (9e)

Compound 9e was obtained from the reaction between 2,3,4,6-tetra-O-benzyl-α/β-d-galactopyranose (820 mg, 1.5 mmol, 1.0 equiv

) and phenylpropiolic acid (469 mg, 2.3 mmol, 1.5 equiv) by following GP-1.

Yield: 785.0 mg (75%, α/β = 1.8:1); pale-yellow liquid; R_f = 0.37 (EtOAc­/hexane 1:10).

¹H NMR (500 MHz, CDCl₃): δ = 7.60 (m, 3 H), 7.49–7.45 (m, 2 H), 7.41–7.27 (m, 36 H), 6.47 (d, J = 3.7 Hz, 0.5 H), 5.71 (d, J = 8.0 Hz, 1 H), 4.97 (dd, J = 11.4, 2.2 Hz, 1 H), 4.90–4.82 (m, 3 H), 4.78 (d, J = 11.7 Hz, 0.7 H), 4.75 (d, J = 4.2 Hz, 3 H), 4.63 (d, J = 11.5 Hz, 1 H), 4.59 (d, J = 11.3 Hz, 0.6 H), 4.51–4.46 (m, 1 H), 4.46–4.39 (m, 2 H), 4.22 (dd, J = 10.1, 3.7 Hz, 0.6 H), 4.17–4.12 (m, 1 H), 4.11–3.98 (m, 3 H), 3.73 (dd, J = 10.0, 3.5 Hz, 1 H), 3.67–3.54 (m, 4 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.7, 152.4, 138.6, 138.4, 138.1, 137.8, 137.7, 133.1, 130.9, 130.7, 128.6, 128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 127.4, 119.5, 119.3, 95.3, 92.5, 88.1, 87.6, 82.2, 80.5, 80.2, 78.6, 77.8, , 75.4, 75.2, 75.0, 74.7, 74.4, 74.3, 73.6, 73.5, 73.1, 73.0, 72.9, 72.1, 68.2, 67.9.

2,3,4-Tri-O-benzyl-α/β-l-rhamnopyranosyl Phenylpropiolate (9f)

Compound 9f was obtained from the reaction between 2,3,4-tri-O-benzyl-α/β-l-rhamnopyranose (160 mg, 0.3 mmol, 1.0 equiv) and phenylpropiolic acid (100 mg, 0.5 mmol, 1.5 equiv) by following GP-1.

Yield: 120 mg (66%, α/β = 2.6:1); pale-yellow liquid; R_f = 0.35 (EtOAc­/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.62–7.55 (m, 4 H), 7.51–7.27 (m, 27 H), 6.22 (d, J = 1.7 Hz, 1 H), 5.67 (d, J = 4 Hz, 0.38 H), 5.00–4.93 (m, 2 H), 4.82–4.72 (m, 2 H), 4.67 (dd, J = 10.7, 3.2 Hz, 2 H), 4.64–4.55 (m, 3 H), 4.00 (d, J = 2.2 Hz, 0.4 H), 3.94–3.86 (m, 2 H), 3.85–3.81 (m, 1 H), 3.72–3.67 (m, 2 H), 3.59 (dd, J = 9.3,2.8 Hz, 0.4 H), 3.50 (dd, J = 9.1, 6.1 Hz, 0.4 H), 1.41 (d, J = 6.1 Hz, 1 H), 1.38 (d, J = 6.2 Hz, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.1, 151.9, 138.2, 138.1, 137.9, 137.8, 137.5, 133.2, 133.1, 132.6, 130.9, 128.7, 128.6, 128.4, 128.3, 128.1, 127.9, 127.8, 127.7, 127.6, 119.3, 119.2, 93.9, 93.1, 88.2, 87.6, 82.0, 80.0, 79.7, 79.5 , 79.2, 75.6, 75.5, 74.2, 73.3, 73.2, 73.0, 72.7, 72.2, , 72.1, 70.8, 18.0, 17.9.

2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl 3-Phenylpropionate (9g)

Compound 9g was obtained from the reaction between 2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranose (100 mg, 0.2 mmol, 1.0 equiv) and 3-phenylpropionic acid (41.0 mg, 1.5 mmol, 1.5 equiv) by following GP-1.

Yield: 93 mg (75%, α/β = 2:1); yellow liquid; R_f = 0.32 (EtOAc/hexane 1:10).

¹H NMR (500 MHz, CDCl₃): δ = 7.34–7.25 (m, 28 H), 7.24–7.21 (m, 3 H), 7.20–7.16 (m, 4 H), 7.14–7.11 (m, 3 H), 6.37 (d, J = 3.6 Hz, 1 H), 5.63 (d, J = 8.2 Hz, 0.49 H), 4.93 (d, J = 10.9 Hz, 1 H), 4.88 (d, J = 10.9 Hz, 0.6), 4.84–4.78 (m, 3 H), 4.73 (d, J = 11.4 Hz, 0.5 H), 4.70–4.66 (m, 2 H), 4.63 (d, J = 4.2 Hz, 1 H), 4.61 (d, J = 3.6 Hz, 0.6 H), 4.58 (d, J = 12.1 Hz, 1 H), 4.50 (dd, J = 13.5, 6.9 Hz, 1 H), 4.47–4.44 (m, 1 H), 3.93–3.87 (m, 1 H), 3.77–3.66 (m, 6 H), 3.61–3.55 (m, 2 H), 2.96 (t, J = 7.8 Hz, 2 H), 2.94–2.90 (m, 1 H), 2.77–2.64 (m, 2 H), 2.60–2.52 (m, 0.3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 171.4, 171.3, 138.6, 138.0, 137.8, 137.6, 94.1, 91.6, 90.1, 84.7, 81.6, 81.0, 78.8, 76.8, 75.7, 75.5, 75.2, 75.0, 74.9, 73.5, 73.1, 72.8, 68.0, 35.8, 30.7, 30.4.

Glycosylation Reaction; General Procedure GP-2

FeCl₃ (10 mol%) was added at r.t. to an oven-dried glass vial containing a glycosyl donor 9a–g (0.1 mmol), a glycosyl acceptor A–O (0.12 mmol, 1.2 equiv), and 4 Å MS in anhydrous DCM (1 mL). The reaction mixture was stirred at 45 °C until completion of the reaction, as monitored by TLC. Then the mixture was diluted with DCM and washed with sat. aq NaHCO₃ (3×). The combined organic phase was washed with brine solution, dried over anhydrous Na₂SO₄, evaporated in vacuo, and purified by column chromatography (silica gel, EtOAc/hexane); this afforded the desired glycoside.

Isopropyl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranoside (11a)

Product 11a was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1.0 equiv) and i-PrOH (I; 9 μL, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 45 mg (75%, α/β = 1.4:1); colorless semisolid; R_f = 0.4 (EtOAc­/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.40–7.27 (m, 30 H), 7.20–7.15 (m, 1 H), 7.13 (dd, J = 7.1, 2.4 Hz, 2 H), 5.04–4.91 (m, 2 H), 4.87 (d, J = 3.7 Hz, 1 H), 4.84 (d, J = 4.4 Hz, 1 H), 4.80 (dd, J = 12.0, 8.1 Hz, 3 H), 4.71 (d, J = 10.8 Hz, 1 H), 4.65 (t, J = 7.4 Hz, 1 H), 4.61 (d, J = 2.4 Hz, 1 H), 4.59–4.51 (m, 1 H), 4.50–4.44 (m, 2 H), 4.07–3.97 (m, 2 H), 3.91 (dd, J = 12.4, 6.2 Hz, 1 H), 3.87–3.81 (m, 1 H), 3.76 (d, J = 3.7 Hz, 1 H), 3.73 (d, J = 3.7 Hz, 1 H), 3.69–3.60 (m, 3 H), 3.59–3.52 (m, 2 H), 3.51–3.41 (m, 2 H), 1.33 (d, J = 6.2 Hz, 2 H), 1.25 (d, J = 6.0 Hz, 4 H), 1.23 (d, J = 6.3 Hz, 3.5 H), 1.18 (d, J = 6.1 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.9, 138.5, 138.2, 137.9, 128.4, 128.3, 128.0, 127.9, 127.7, 127.5, 102.2, 94.7, 84.8, 82.3, 82.1, 79.9, 78.0, 77.8, 75.7, 75.1, 74.8, 73.4, 73.2, 72.4, 70.0, 69.1, 68.9, 68.5, 23.7, 23.2, 22.2, 21.1.

2,3,4-Tri-O-benzyl-α/β-d-glucopyranosyl-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (11b)

Product 11b was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and A (28 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 53 mg (68%, α/β = 1.5:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.44–7.27 (m, 26 H), 7.17–7.12 (m, 3 H), 5.57 (d, J = 5.0 Hz, 0.45 H), 5.52 (d, J = 5.0 Hz, 1 H), 5.08–4.93 (m, 3 H), 4.85–4.76 (m, 4 H), 4.71 (t, J = 9.2 Hz, 2 H), 4.69–4.44 (m, 8 H), 4.36 (dd, J = 7.9, 1.7 Hz, 1 H), 4.31 (dd, J = 4.8, 2.3 Hz, 1 H), 4.29–4.21 (m, 0.5 H), 4.19–4.13 (m, 0.5 H), 4.11– 3.97 (m, 3 H), 3.87–3.41 (m, 12 H), 1.54 (s, 4.6 H), 1.51 (s, 4.4 H), 1.45 (s, 4 H), 1.32 (d, J = 5.2 Hz, 8 H).

¹³C NMR (125 MHz, CDCl₃): δ = 139.0, 138.7, 138.4, 138.0, 128.6, 128.3, 128.2, 127.9, 127.8, 127.7, 127.6, 127.5, 109.4, 109.2, 108.6, 104.4, 97.1, 96.4, 96.3, 84.6, 82.0, 81.7, 79.8, 77.8, 77.6, 75.6, 74.9, 74.8, 74.3, 73.5, 72.4, 71.4, 70.8, 70.7, 70.5, 70.3, 69.7, 68.8, 68.4, 67.4, 26.2, 26.1, 26.0, 24.9, 24.6, 24.4.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (11c)

Product 11c was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and B (64 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 69 mg (71%, α/β = 3.5:1); semi-solid.

¹H NMR (400 MHz, CDCl₃): δ = 7.35–7.28 (m, 36 H), 7.24–7.10 (m, 7 H), 5.00–4.88 (m, 3 H), 4.84–4.76 (m, 4 H), 4.74–4.51 (m, 11 H), 4.49–4.34 (m, 4 H), 4.05–3.87 (m, 2 H), 3.85–3.41 (m, 12 H), 3.36 (s, 3 H), 3.33 (s, 0.84 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.5, 138.4, 138.3, 138.2, 138.1, 128.4, 128.3, 128.0, 127.9, 127.7, 127.6, 103.8, 98.0, 97.9, 97.2, 84.8, 81.9, 81.7, 80.1, 80.0, 79.8, 78.0, 77.9, 77.7, 77.6, 77.3, 75.7, 75.5, 75.0, 74.9, 73.4, 73.3, 72.4, 70.3, 69.8, 69.0, 68.5, 55.2, 55.1.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-mannopyranoside (11d)

Product 11d was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and C (64 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 69 mg (50%, α/β = 1.6:1); sticky liquid.

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.27 (m, 49 H), 7.24–7.20 (m, 9 H), 7.17 (dd, J = 7.1, 2.3 Hz, 1 H), 7.12 (dd, J = 7.1, 2.2 Hz, 2 H), 5.10 (d, J = 3.4 Hz, 1 H), 5.07–4.89 (m, 4 H), 4.79 (dt, J = 13.5, 11.1 Hz, 6 H), 4.72–4.54 (m, 17 H), 4.52–4.38 (m, 4 H), 4.00 (t, J = 9.4 Hz, 3 H), 3.94–3.75 (m, 10 H), 3.74–3.42 (m, 10 H), 3.28 (s, 1.8 H), 3.25 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 139.5, 138.9, 138.5, 138.4, 138.3, 138.1, 137.9, 137.8, 128.4, 128.3, 128.2, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 127.2, 127.0, 126.7, 102.4, 98.4, 97.7, 96.6, 84.8, 82.8, 81.9, 80.4, 80.2, 78.8, 78.0, 75.5, 75.3, 75.1, 74.8, 74.7, 74.3, 73.6, 73.4, 73.3, 73.2, 72.4, 70.9, 69.9, 69.5, 69.0, 67.8, 55.2, 55.1.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzyl-1-thio-β-d-glucopyranoside (11e)

Product 11e was isolated from the reaction between 9a (33 mg, 0.05 mmol, 1 equiv) and D (32 mg, 0.06 mmol, 1.2 equiv) by following GP-2.

Yield: 35 mg (67%, α/β = 2.1:1); colorless sticky liquid; R_f = 0.45 (EtOAc­/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.56–7.53 (m, 2 H), 7.42–7.26 (m, 39 H), 7.25–7.15 (m, 11 H), 7.12 (dd, J = 7.0, 2.5 Hz, 1 H), 5.01 (dd, J = 18.0, 7.2 Hz, 1 H), 4.97–4.91 (m, 1.5 H), 4.91–4.89 (m, 1 H), 4.89–4.84 (m, 0.6 H), 4.83 (d, J = 2.1 Hz, 1 H), 4.82–4.79 (m, 1 H), 4.77 (dd, J = 7.7, 3.0 Hz, 1 H), 4.74 (d, J = 4.5 Hz, 1 H), 4.72 (d, J = 2.7 Hz, 1 H), 4.73–4.70 (m, 1 H), 4.69–4.65 (m, 1 H), 4.63–4.61(m, 1 H), 4.59 (d, J = 7.5 Hz, 2 H), 4.56 (dd, J = 6.1, 3.0 Hz, 1 H), 4.53 (d, J = 11.9 Hz, 1 H), 4.49–4.43 (m, 1 H), 4.41 (d, J = 7.8 Hz, 1 H), 4.19 (dd, J = 11.1, 1.8 Hz, 0.60 H), 3.99 (t, J = 9.3 Hz, 0.5 H), 3.92 (dd, J = 7.2, 1.0 Hz, 0.25 H), 3.88–3.83 (m, 1 H), 3.78 (dd, J = 11.7, 1.7 Hz, 0.5 H), 3.75–3.58 (m, 9 H), 3.52–3.39 (m, 3 H), 3.27 (dd, J = 9.8, 8.5 Hz, 0.5 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.4, 138.0, 134.0, 132.0, 131.3, 129.0, 128.9, 128.5, 128.4, 128.3, 128.2, 128.1, 103.8, 100.6, 97.4, 94.0, 88.1, 87.2, 86.7, 86.6, 84.6, 82.2, 81.7, 81.0, 80.8, 80.0, 78.8, 78.7, 77.8, 77.5, 75.7, 75.6, 75.5, 75.4, 75.0, 74.9, 74.8, 73.5, 73.3, 72.4, 71.8, 71.1, 70.1, 68.7, 66.2.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-β-d-glucopyranoside (11f)

Product 11f was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and E (60 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 42 mg (57%, α/β = 3.5:1); colorless semi-solid; R_f = 0.4 (EtOAc­/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 8.07–7.97 (m, 5 H), 7.90–7.83 (m, 2 H), 7.63–7.38 (m, 22 H), 7.37–7.27 (m, 19 H), 7.25–7.16 (m, 5 H), 5.95 (dt, J = 15.8, 9.5 Hz, 1 H), 5.58–5.45 (m, 2 H), 5.13 (d, J = 10.1 Hz, 0.3 H), 5.06 (d, J = 10.0 Hz, 1 H), 5.00 (d, J = 11.0 Hz, 1 H), 4.90 (d, J = 7.8 Hz, 0.6 H), 4.89 (d, J = 2.0 Hz, 1 H), 4.85 (d, J = 12.1 Hz, 2 H), 4.73 (d, J = 3.5 Hz, 1 H), 4.67 (d, J = 12.1 Hz, 2 H), 4.62–4.54 (m, 2 H), 4.50 (d, J = 12.1 Hz, 1 H), 4.27–4.12 (m, 2 H), 4.05–3.95 (m, 3 H), 3.85–3.80 (m, 2 H), 3.78–3.67 (m, 4 H), 3.65–3.58 (m, 2 H), 3.53–3.44 (m, 1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 165.7, 165.4, 165.1, 138.9, 138.4, 138.2, 137.9, 133.5, 133.3, 133.2, 132.8, 132.4, 132.2, 129.9, 129.7, 129.1, 128.4, 128.3, 128.2, 128.1, 127.9, 127.7, 127.6, 103.9, 97.3, 86.9, 81.9, 80.0, 77.6, 77.3, 77.2, 77.1, 76.8, 75.7, 74.9, 74.2, 73.5, 73.3, 70.5, 70.1, 69.5, 68.2, 68.0, 67.2, 60.4.

HRMS (ESI/Q-TOF): m/z [M + H]⁺ calcd for C₆₇H₆₂O₁₃S: 1129.3803; found: 1129.3826.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-benzyl-α-d-glucopyranoside (11g)

Product 11g was isolated from the reaction between 9a (60 mg, 0.09 mmol, 1 equiv) and F (46 mg, 0.1 mmol, 1.2 equiv) by following GP-2.

Yield: 62 mg (71%, α/β = 1:1); colorless sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.43–7.39 (m, 2 H), 7.34–7.24 (m, 49 H), 7.22–7.16 (m, 14 H), 7.11–7.07 (m, 2 H), 5.10–5.02 (m, 1 H), 4.90–4.65 (m, 12 H), 4.62–4.47 (m, 12 H), 4.46–4.35 (m, 5 H), 4.26 (d, J = 12.1 Hz, 1 H), 4.11–3.78 (m, 7 H), 3.74–3.45 (m, 14 H), 3.37 (s, 3 H), 3.35 (s, 2.6 H).

¹³C NMR (125 MHz, CDCl₃): δ = 139.7, 138.6, 138.0, 128.6, 128.5, 128.4, 128.1, 128.0, 127.6, 127.3, 127.2, 126.9, 102.6, 98.5, 97.9, 96.7, 84.9, 82.9, 82.1, 80.3, 73.8, 73.5, 73.4, 73.1, 72.2, 71.0, 70.0, 69.5, 55.4, 55.3.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranosyl-(1→3)-2-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (11h)

Product 11h was isolated from the reaction between 9a (60 mg, 0.09 mmol, 1 equiv) and G (40 mg, 0.1 mmol, 1.2 equiv) by following GP-2.

Yield: 54 mg (70%, α only); colorless sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.27 (m, 16 H), 7.25–7.13 (m, 8 H), 7.10–7.07 (m, 4 H), 6.92 (d, J = 7.3 Hz, 2 H), 5.59 (d, J = 3.6 Hz, 1 H), 5.47 (s, 1 H), 4.99 (d, J = 10.8 Hz, 1 H), 4.80 (dd, J = 10.9, 4.3 Hz, 2 H), 4.71 (d, J = 3.7 Hz, 1 H), 4.65 (d, J = 11.2 Hz, 1 H), 4.62–4.53 (m, 3 H), 4.44–4.32 (m, 3 H), 4.29 (d, J = 12.0 Hz, 1 H), 4.27–4.17 (m, 2 H), 3.97 (t, J = 9.3 Hz, 1 H), 3.90–3.84 (m, 1 H), 3.82–3.63 (m, 5 H), 3.54–3.45 (m, 3 H), 3.41 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.9, 138.8, 138.0, 137.8, 137.4, 137.0, 128.7, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.6, 127.5, 127.4, 127.3, 126.4, 102.1, 98.5, 96.1, 82.9, 81.6, 78.7, 78.0, 75.5, 74.8, 73.4, 73.3, 72.7, 71.1, 69.8, 69.2, 68.1, 61.7, 55.3.

Methyl 2,3,4,6-Tetra-O-benzyl-α-d-glucopyranosyl-(1→2)-3-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (11i)

Product 11i was isolated from the reaction between 9a (60 mg, 0.09 mmol, 1 equiv) and H (40 mg, 0.1 mmol, 1.2 equiv) by following GP-2.

Yield: 35 mg (44%, α/β = 3:1); colorless sticky liquid; R_f = 0.5 (EtOAc­/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.51 (dd, J = 7.8, 1.7 Hz, 2 H), 7.42–7.27 (m, 25 H), 7.25–7.07 (m, 10 H), 7.02 (dd, J = 10.7, 4.4 Hz, 2 H), 6.91 (d, J = 7.2 Hz, 0.5 H), 5.59 (d, J = 3.6 Hz, 0.29 H), 5.57 (s, 1 H), 5.47 (s, 0.34 H), 5.00 (d, J = 12.1 Hz, 1 H), 4.89 (dd, J = 7.5, 3.8 Hz, 2 H), 4.86–4.78 (m, 4 H), 4.75 (d, J = 10.2 Hz, 1 H), 4.73–4.69 (m, 1 H), 4.62–4.51 (m, 2 H), 4.46–4.36 (m, 2 H), 4.30 (m, 3 H), 4.14–4.10 (m, 3 H), 3.89–3.83 (m, 2 H), 3.82–3.57 (m, 6 H), 3.47 (s, 3 H), 3.42 (s, 1 H), 3.38 (dd, J = 10.9, 2.0 Hz, 1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.6, 138.4, 137.9, 137.8, 137.3, 128.4, 128.3, 128.2, 128.0, 127.8, 126.0, 102.1, 101.2, 98.4, 97.1, 96.1, 94.4, 82.8, 82.3, 82.1, 81.6, 79.0, 78.6, 77.6, 75.8, 75.7, 74.9, 74.1, 73.2, 73.1, 69.8, 69.0, 67.9, 62.2, 61.7, 55.3, 55.0.

1-Adamantanol 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranoside (11j)

Product 11j was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and 1-adamantanol (J; 18 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 36 mg (75%, α/β = 1:1); semi-solid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.39–7.26 (m, 28 H), 7.25–7.12 (m, 4 H), 5.28 (d, J = 3.6 Hz, 1 H), 5.02 (d, J = 7.5 Hz, 0.7 H), 5.00 (d, J = 7.3 Hz, 1 H), 4.92 (d, J = 10.9 Hz, 0.6 H), 4.87–4.78 (m, 3 H), 4.77–4.63 (m, 5 H), 4.60–4.52 (m, 2 H), 4.47 (d, J = 1.6 Hz, 1 H), 4.44 (d, J = 3.5 Hz, 1 H), 4.05–4.00 (m, 2 H), 3.81–3.72 (m, 3 H), 3.70–3.59 (m, 1 H), 3.57–3.51 (m, 1 H), 3.50–3.41 (m, H), 2.14 (br s, 5 H), 1.96–1.80 (m, 10 H), 1.63–1.58 (m, 11 H).

¹³C NMR (100 MHz, CDCl₃): δ = 139.0, 138.6, 138.5, 138.3, 138.2, 138.0, 128.4, 128.3, 128.2, 128.0, 127.9, 127.8, 127.6, 96.2, 89.8, 85.1, 82.3, 82.0, 80.0, 78.1, 78.0, 75.5, 75.1, 74.9, 74.5, 73.4, 73.3, 72.8, 69.6, 69.4, 68.6, 42.7, 42.4, 36.2, 30.6.

(+)-Menthol 2,3,4,6-Tetra-O-benzyl-α-d-glucopyranoside (11k)

Product 11k was isolated from the reaction between 9a (33 mg, 0.05 mmol, 1 equiv) and (+)-menthol (K; 9 mg, 0.06 mmol, 1.2 equiv) by following GP-2.

Yield: 25 mg (72%, α/β = 3.2:1); sticky liquid; R_f = 0.30 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.26 (m, 23 H), 7.21 (d, J = 7.6 Hz, 1 H), 7.16–7.11 (m, 2 H), 5.01 (d, J = 4.0 Hz, 1 H), 4.99 (d, J = 2.6 Hz, 1 H), 4.90 (s, 1 H), 4.82 (d, J = 10.8 Hz, 2 H), 4.81–4.73 (m, 2 H), 4.66 (d, J = 10.7 Hz, 1 H), 4.60 (dd, J = 7.8, 5.6 Hz, 2 H), 4.50 (s, 1 H), 4.47–4.42 (m, 1 H), 3.94 (t, J = 9.4 Hz, 1 H), 3.79 (d, J = 9.0 Hz, 2 H), 3.76–3.62 (m, 2 H), 3.58 (dd, J = 9.6, 3.8 Hz, 2 H), 3.51–3.38 (m, 2 H), 2.31–2.21 (m, 1 H), 1.98 (d, J = 11.6 Hz, 1 H), 1.65 (d, J = 12.6 Hz, 2 H), 1.47–1.21 (m, 5 H), 1.21–1.10 (m, 1 H), 0.95–0.86 (m, 13 H), 0.70 (d, J = 6.9 Hz, 4 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.9, 138.1, 138.0, 137.9, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.6, 127.5, 104.4, 93.4, 82.0, 79.8, 77.7, 75.6, 75.4, 75.2, 73.6, 73.5, 70.6, 68.4, 47.2, 39.7, 34.3, 31.3, 25.0, 22.6, 22.4, 21.0, 15.8, 15.0.

(–)-Menthol 2,3,4,6-Tetra-O-benzyl-α-d-glucopyranoside (11l)

Product 11l was isolated from the reaction between 9a (33 mg, 0.05 mmol, 1 equiv) and (–)-menthol (L; 9 mg, 0.06 mmol, 1.2 equiv) by following GP-2.

Yield: 23 mg (68%, α/β = 3.2:1); sticky liquid; R_f = 0.30 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.37–7.26 (m, 18 H), 7.16–7.11 (m, 2 H), 5.02 (d, J = 3.4 Hz, 1 H), 4.97 (d, J = 10.9 Hz, 1 H), 4.83 (dd, J = 10.8, 5.9 Hz, 2 H), 4.69 (d, J = 3.8 Hz, 2 H), 4.64 (d, J = 12.2 Hz, 1 H), 4.46 (dd, J = 11.4, 4.4 Hz, 2 H), 4.00 (dd, J = 20.6, 11.2 Hz, 2 H), 3.75 (dd, J = 10.5, 3.6 Hz, 1 H), 3.68–3.60 (m, 2 H), 3.54 (dd, J = 9.8, 3.5 Hz, 1 H), 3.35 (td, J = 10.6, 4.2 Hz, 1 H), 2.47–2.37 (m, 1 H), 1.60 (s, 4 H), 1.40–1.23 (m, 3 H), 1.10–0.92 (m, 2 H), 0.85 (dd, J = 14.4, 9.2 Hz, 7 H), 0.70 (d, J = 6.9 Hz, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.9, 138.3, 138.0, 128.3, 128.2, 127.8, 127.6, 98.6, 81.9, 81.0, 80.5, 78.1, 75.4, 75.0, 73.4, 73.1, 70.3, 68.7, 48.7, 43.0, 34.2, 31.7, 30.9, 24.6, 22.9, 22.2, 21.0, 16.0.

Cholesteryl 2,3,4,6-Tetra-O-benzyl-α/β-d-glucopyranoside (11m)

Product 11m was isolated from the reaction between 9a (67 mg, 0.1 mmol, 1 equiv) and cholesterol (N; 46 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 64 mg (72%, α/β = 1:1); white solid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.38–7.27 (m, 27 H), 7.19–7.12 (m, 3 H), 5.35 (d, J = 9.4 Hz, 1 H), 5.29 (d, J = 5.1 Hz, 0.6 H), 4.99 (dd, J = 16.3, 10.8 Hz, 1.4 H), 4.95–4.90 (m, 1.4 H), 4.84–4.76 (m, 4 H ), 4.72 (d, J = 10.9 Hz, 0.7 H), 4.68–4.58 (m, 2 H), 4.57–4.49 (m, 2 H), 4.46 (dd, J = 11.3, 5.0 Hz, 1 H), 4.01 (t, J = 9.3 Hz, 0.6 H), 3.91–3.85 (m, 0.6 H), 3.77–3.71 (m, 1 H), 3.68–3.52 (m, 5 H), 3.50–3.41 (m, 2 H), 2.47–2.23 (m, 3 H), 2.07–1.79 (m, 9 H), 1.72–1.30 (m, 24 H), 1.19–1.05 (m, 13 H), 1.02 (d, J = 10.8 Hz, 11 H), 0.92 (d, J = 6.4 Hz, 7 H), 0.87 (dd, J = 6.6, 2.2 Hz, 14 H), 0.68 (d, J = 2.7 Hz, 6 H).

¹³C NMR (125 MHz, CDCl₃): δ = 140.8, 138.9, 138.2, 137.9, 128.4, 128.3, 128.2, 128.0, 127.9, 127.7, 122.2, 121.9, 121.7, 102.2, 94.5, 84.8, 82.3, 82.1, 79.8, 79.7, 77.9, 77.8, 75.7, 75.5, 75.2, 75.0, 74.7, 73.7, 73.5, 73.4, 73.3, 73.2, 73.1, 72.7, 72.4, 72.2, 71.8, 71.7, 70.8, 69.9, 69.3, 69.1, 68.8, 68.4, 56.7, 56.1, 50.1, 50.0, 42.3, 39.7, 39.5, 36.1, 35.8, 31.8, 28.2, 28.0, 24.3, 23.8, 22.8, 22.6, 21.0, 19.4, 19.4, 18.7, 11.8.

2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (12a)

Product 12a was isolated from the reaction between 9b (52 mg, 0.06 mmol, 1 equiv) and B (36 mg, 0.07 mmol, 1.2 equiv) by following GP-2.

Yield: 51 mg (69%, α/β = 1.2:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.78–7.63 (m, 6 H), 7.43–7.27 (m, 44 H), 7.25–7.11 (m, 12 H), 5.00–4.88 (m, 7 H), 4.86–4.76 (m, 4 H), 4.74–4.48 (m, 11 H), 4.46–4.30 (m, 1 H), 4.93–3.90 (m, 5 H), 3.86–3.52 (m, 13 H), 3.39 (s, 2.11 H), 3.36 (s, 3 H), 1.02 (d, J = 3.2 Hz, 12 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.5, 138.4, 138.3, 138.1, 135.8, 135.5, 129.6, 129.5, 128.4, 128.4, 128.3, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 103.8, 98.2, 97.9, 96.9, 82.6, 82.2, 82.0, 81.7, 80.9, 80.4, 80.0, 79.6, 75.8, 75.6, 75.1, 74.9, 74.3, 74.7, 73.3, 72.3, 71.9, 71.7, 71.5, 71.1, 70.4, 55.2, 55.0, 26.5, 19.2, 19.2.

2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranosyl-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (12b)

Product 12b was isolated from the reaction between 9b (40 mg, 0.05 mmol, 1 equiv) and A (15 mg, 0.06 mmol, 1.2 equiv) by following GP-2.

Yield: 32 mg (68%, α/β = 1.5:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.76 (dd, J = 7.8, 1.6 Hz, 2 H), 7.73–7.66 (m, 7 H), 7.45–7.27 (m, 42 H), 7.21–7.16 (m, 4 H), 5.58 (d, J = 5.0 Hz, 0.8 H), 5.51 (d, J = 5.0 Hz, 1 H), 5.08–5.05 (m, 2 H), 4.99–4.88 (m, 4 H), 4.81 (dd, J = 10.9, 7.1 Hz, 3 H), 4.75–4.65 (m, 4 H), 4.61–4.59 (m, 2 H), 4.48 (d, J = 7.8 Hz, 1 H), 4.36–4.26 (m, 4 H), 4.22–4.09 (m, 2 H), 4.06–3.99 (m, 2 H), 3.97–3.85 (m, 5 H), 3.79–3.73 (m, 5 H), 3.71–3.63 (m, 2 H), 3.60 (dd, J = 9.6, 3.7 Hz, 1 H), 3.53–3.46 (m, 1 H), 3.34–3.31 (m, 1 H), 1.51 (d, J = 6.3 Hz, 6 H), 1.46 (d, J = 2.7 Hz, 6 H), 1.32 (dd, J = 6.5, 3.6 Hz, 12 H), 1.05 (d, J = 6.0 Hz, 18 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.7, 138.6, 138.4, 138.3, 138.2, 135.9, 135.8, 135.6, 133.6, 133.2, 133.1, 129.6, 129.5, 128.5, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.7, 127.6, 127.5, 109.3, 109.1, 108.5, 104.0, 96.3, 96.2, 84.6, 82.1, 82.0, 80.2, 77.5, 75.9, 75.5, 75.1, 74.5, 72.2, 71.4, 71.2, 70.7, 70.6, 70.5, 68.9, 67.1, 65.4, 65.3, 62.5, 26.8, 26.7, 26.1, 26.0, 25.0, 24.9, 24.6, 24.4, 19.3.

Phenyl-O-(2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzyl-1-thio-β-d-glucopyranoside (12c)

Product 12c was isolated from the reaction between 9b (60 mg, 0.07 mmol, 1 equiv) and D (48 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 61 mg (69%, α/β = 3.7:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.72 (dd, J = 8.0, 1.4 Hz, 3 H), 7.67 (dd, J = 8.0, 1.4 Hz, 3 H), 7.57 (dd, J = 8.2, 1.1 Hz, 3 H), 7.44–7.27 (m, 40 H), 7.25–7.23 (m, 8 H), 7.19–7.14 (m, 4 H), 5.09 (d, J = 3.5 Hz, 1 H), 4.97 (d, J = 10.7 Hz, 1 H), 4.92 (d, J = 10.9 Hz, 1 H), 4.89–4.78 (m, 8 H), 4.73 (d, J = 12.0 Hz, 1 H), 4.66 (s, 2 H), 4.65–4.60 (m, 3 H), 4.00 (d, J = 9.2 Hz, 1 H), 3.90–3.75 (m, 7 H), 3.68 (dt, J = 17.9, 9.7 Hz, 4 H), 3.58 (dd, J = 9.6, 3.5 Hz, 1 H), 3.50–3.46 (m, 1 H), 3.26–3.21 (m, 1 H), 1.06 (s, 2 H), 1.05 (s, 9 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.7, 138.5, 138.4, 137.9, 135.8, 135.6, 133.6, 132.3, 129.5, 128.9, 128.4, 128.3, 128.2, 127.8, 127.7, 127.6, 127.5, 127.4, 101.0, 96.9, 87.8, 86.5, 81.7, 81.0, 80.5, 78.9, 75.8, 75.6, 75.4, 75.0, 74.9, 72.3, 71.5, 65.5, 62.7, 60.4, 29.7, 26.8, 21.0, 19.3.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₇₆H₈₀O₁₀SSi: 1235.5134; found: 1235.5193.

Phenyl-O-(2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-β-d-glucopyranoside (12d)

Product 12d was isolated from the reaction between 9b (50 mg, 0.06 mmol, 1 equiv) and E (37 mg, 0.07 mmol, 1.2 equiv) by following GP-2.

Yield: 41 mg (57%, α/β = 5.5:1); colorless semi-solid; R_f = 0.4 (EtOAc­/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.98–7.95 (m, 2 H), 7.93–7.88 (m, 2 H), 7.80–7.75 (m, 2 H), 7.72–7.62 (m, 5 H), 7.56–7.45 (m, 5 H), 7.43–7.37 (m, 10 H), 7.36–7.30 (m, 15 H), 7.28 (dd, J = 5.5, 3.8 Hz, 2 H), 7.25–7.20 (m, 7 H), 7.19–7.11 (m, 6 H), 5.91 (t, J = 9.5 Hz, 0.2 H), 5.85 (t, J = 9.5 Hz, 1 H), 5.49–5.41 (m, 2 H), 5.07 (d, J = 10.0 Hz, 0.2 H), 5.01–4.87 (m, 4 H), 4.83–4.77 (m, 2 H), 4.70 (d, J = 3.6 Hz, 1 H), 4.64 (dd, J = 11.5, 6.3 Hz, 2 H), 4.16–4.08 (m, 2 H), 4.00 (t, J = 9.4 Hz, 1 H), 3.93–3.83 (m, 5 H), 3.78–3.62 (m, 2 H), 3.55 (dd, J = 9.7, 3.6 Hz, 1 H), 3.50 (dd, J = 10.9, 1.7 Hz, 1 H), 1.06 (s, 9 H), 1.01 (s, 1.7 H).

¹³C NMR (125 MHz, CDCl₃): δ = 165.7, 165.1, 165.0, 138.8, 138.5, 138.3, 135.8, 135.6, 133.5, 133.3, 133.2, 133.1, 132.3, 132.2, 129.9, 129.7, 129.5, 129.1, 128.4, 128.2, 128.1, 128.0, 127.6, 127.5, 96.9, 86.8, 81.9, 80.5, 77.6, 75.9, 75.0, 74.3, 73.4, 71.6, 70.5, 69.5, 66.8, 62.6, 26.8, 26.7, 19.3, 19.2.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₇₆H₇₄O₁₃SSi: 1277.4512; found: 1277.4500.

(±)-Menthol 2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranoside (12e)

Product 12e was isolated from the reaction between 9b (53 mg, 0.065 mmol, 1 equiv) and (±)-menthol (M; 12 mg, 0.078 mmol, 1.2 equiv) by following GP-2.

Yield: 37 mg (70%, α(+)/α(–)/β = 2.7:1.6:1); colorless semi-solid; R_f = 0.4 (EtOAc/hexane 1:9).

¹H NMR (400 MHz, CDCl₃): δ = 7.76–7.65 (m, 6 H), 7.45–7.27 (m, 28 H), 7.21 (m, 3 H), 7.10–7.03 (m, 1 H), 5.05–4.90 (m, 4 H), 4.87 (s, 1 H), 4.81 (t, J = 11.5 Hz, 2 H), 4.73 (dd, J = 12.6, 8.6 Hz, 2 H), 4.65 (d, J = 10.7 Hz, 0.5 H), 4.55 (d, J = 7.5 Hz, 0.3 H), 4.04 (d, J = 9.4 Hz, 0.3 H), 3.99 (dd, J = 10.8, 7.8 Hz, 0.5 H), 3.89 (m, 1 H), 3.81 (d, J = 4.3 Hz, 2 H), 3.79–3.64 (m, 0.4 H), 3.57 (m, 2 H), 3.46 (t, J = 8.4 Hz, 0.3 H), 3.41 (dd, J = 10.6, 3.9 Hz, 0.6 H), 3.38–3.31 (m, 1 H), 2.46–2.38 (m, 0.5 H), 2.36–2.32 (m, 0.3 H), 2.19 (dd, J = 7.1, 4.5 Hz, 1 H), 2.04 (d, J = 9.7 Hz, 6 H), 1.73–1.55 (m, 2 H), 1.42 (s, 5 H), 1.33–1.24 (m, 14 H), 1.05 (d, J = 3.1 Hz, 10 H), 0.98 (d, J = 6.5 Hz, 4 H), 0.92 (d, J = 6.9 Hz, 4 H), 0.88–0.72 (m, 10 H), 0.55 (d, J = 6.9 Hz, 2 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.8, 138.7, 138.5, 138.3, 138.2, 135.9, 135.8, 135.6, 133.7, 133.3, 133.2, 129.6, 129.5, 128.5, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.7, 127.6, 127.5, 127.4, 99.9, 98.1, 93.1, 85.1, 82.4, 82.1, 82.0, 80.9, 80.4, 78.1, 77.8, 77.6, 75.9, 75.8, 75.7, 75.5, 75.4, 75.2, 74.9, 73.6, 73.3, 71.7, 71.5, 63.0, 62.7, 62.4, 48.7, 48.1, 47.2, 42.8, 40.4, 39.9, 34.3, 34.2, 31.7, 31.6, 31.5, 29.6, 26.8, 26.7, 25.6, 24.9, 24.6, 22.9, 22.6, 22.4, 22.3, 22.2, 21.1, 21.0, 19.3, 16.3, 16.0, 15.1.

Cholesteryl 2,3,4-Tri-O-benzyl-6-O-(tert-butyldiphenylsilyl)-α/β-d-glucopyranoside (12f)

Product 12f was isolated from the reaction between 9b (55 mg, 0.07 mmol, 1 equiv) and cholesterol (N; 31 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 48 mg (66%, α/β = 1.3:1); colorless sticky liquid; R_f = 0.4 (EtOAc/hexane 1:9).

¹H NMR (400 MHz, CDCl₃): δ = 7.75–7.66 (m, 8 H), 7.46–7.29 (m, 32 H), 7.18–7.12 (m, 3 H), 5.36 (d, J = 5.0 Hz, 4 H), 5.23 (d, J = 4.8 Hz, 0.7 H), 5.05–4.97 (m, 1.7 H), 4.93 (d, J = 10.8 Hz, 3 H), 4.90–4.86 (m, 1 H), 4.85 (d, J = 2.2 Hz, 1 H), 4.81 (d, J = 12.3 Hz, 1 H), 4.75 (d, J = 10.9 Hz, 2 H), 4.70 (d, J = 12.0 Hz, 1 H), 4.64 (d, J = 10.7 Hz, 1 H), 4.58 (d, J = 10.7 Hz, 1 H), 4.53 (d, J = 7.8 Hz, 1 H), 4.05 (t, J = 9.3 Hz, 1 H), 3.93–3.82 (m, 5 H), 3.68–3.46 (m, 7 H), 2.45–2.24 (m, 1 H), 2.09–1.81 (m, 9 H), 1.57–1.48 (m, 12 H), 1.42 (s, 5 H), 1.30 (s, 4 H), 1.20–1.09 (m, 10 H), 1.05–1.00 (d, J = 7.7 Hz, 19 H), 1.00 (s, 6 H), 0.94–0.90 (m, 7 H), 0.87 (d, J = 6.6 Hz, 13 H), 0.69 (d, J = 7.6 Hz, 5 H).

¹³C NMR (125 MHz, CDCl₃): δ = 140.6, 140.5, 138.8, 138.6, 138.3, 138.1, 135.8, 135.6, 133.5, 133.2, 133.1, 129.6, 129.5, 128.4, 128.1, 128.0, 127.8, 127.7, 127.6, 127.5, 124.1, 123.5, 121.9, 121.8, 102.4, 93.8, 84.9, 82.6, 82.1, 80.2, 79.7, 78.0, 77.7, 75.9, 75.6 75.2, 75.1, 75.0, 73.0, 71.5, 63.0, 62.8, 56.7, 56.1, 50.1, 50.0, 42.3, 39.7, 39.5, 39.1, 37.3, 37.0, 36.7, 36.1, 35.8, 31.9, 31.8, 31.6, 30.1, 29.6, 28.2, 28.0, 27.2, 26.8, 26.7, 24.3, 23.8, 22.8, 22.6, 21.0, 19.4, 19.2, 18.7, 11.8.

4,6-O-Benzylidene-2,3-di-O-benzyl-α/β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (13a)

Product 13a was isolated from the reaction between 9c (40 mg, 0.07 mmol, 1 equiv) and B (22 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 33 mg (67%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.45–7.42 (m, 2 H), 7.36–7.27 (m, 23 H), 7.25–7.20 (m, 14 H), 7.17 (d, J = 2.8 Hz, 3 H), 5.52 (s, 0.4 H), 5.50 (s, 1 H), 4.94 (d, J = 10.8 Hz, 2 H), 4.91–4.83 (m, 4 H), 4.81–4.73 (m, 5 H), 4.73–4.57 (m, 6 H), 4.56–4.52 (m, 2 H), 4.47–4.40 (m, 1 H), 4.17 (dd, J = 10.2, 4.8 Hz, 1 H), 4.08 (dd, J = 10.7, 2.0 Hz, 0.3 H), 3.96 (dd, J = 17.4, 9.2 Hz, 3 H), 3.86 (td, J = 10.0, 4.9 Hz, 1 H), 3.80–3.63 (m, 7 H), 3.61–3.53 (m, 2 H), 3.52–3.37 (m, 4 H), 3.31 (s, 3 H), 3.30 (s, 1.1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.7, 138.6, 138.3, 138.1, 137.4, 129.0, 128.8, 128.4, 128.3, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 127.5, 126.0, 125.9, 101.2, 101.1, 98.1, 97.9, 82.0, 81.7, 81.0, 79.9, 79.6, 79.2, 77.8, 77.6, 75.7, 75.0, 73.4, 73.3, 72.8, 70.3, 69.6, 69.0, 66.3, 62.5, 55.2, 55.1.

4,6-O-Benzylidene-2,3-di-O-benzyl-α/β-d-glucopyranosyl-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (13b)

Product 13b was isolated from the reaction between 9c (40 mg, 0.07 mmol, 1 equiv) and A (22 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 33 mg (67%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.81–7.73 (m, 1 H), 7.56–7.27 (m, 18 H), 5.57 (s, 0.3 H), 5.56 (s, 1 H), 5.02 (d, J = 11.1 Hz, 0.3 H), 4.96–4.92 (m, 1 H), 4.90 (d, J = 10.7 Hz, 1 H), 4.84 (d, J = 11.3 Hz, 1 H), 4.78 (dd, J = 16.4, 4.4 Hz, 2 H), 4.62–4.56 (m, 2 H), 4.38–4.27 (m, 3 H), 4.25–4.20 (m, 1 H), 4.12–3.99 (m, 2 H), 3.94–3.89 (m, 1 H), 3.80–3.56 (m, 5 H), 3.48 (dd, J = 8.5, 7.9 Hz, 0.3 H), 3.41 (td, J = 9.9, 5.0 Hz, 0.3 H), 1.62 (s, 2 H), 1.54 (d, J = 7.4 Hz, 3 H), 1.46 (s, 3 H), 1.41–1.36 (m, 1 H), 1.33 (d, J = 5.7 Hz, 8 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.4, 138.2, 137.4, 132.1, 132.0, 129.0, 128.9, 128.5, 128.3, 128.4, 128.3, 128.2, 128.2, 128.0, 127.9, 127.9, 127.7, 127.5, 126.0, 125.9, 125.5, 125.4, 109.5, 109.4, 109.1, 108.8, 108.6, 108.5, 104.9, 101.1, 101.0, 98.3, 96.3, 96.2, 82.0, 81.4, 81.3, 80.6, 79.1, 78.5, 75.2, 75.1, 74.8, 72.8, 70.7, 70.5, 68.9, 68.8, 67.2, 67.1, 66.9, 66.8, 65.9, 65.8, 64.9, 63.1, 62.4, 26.1, 26.0, 25.9, 25.8, 24.9, 24.6, 24.4.

1-Adamantanemethanol-4,6-O-benzylidene-2,3-di-O-benzyl-α-d-glucopyranoside (13c)

Product 13c was isolated from the reaction between 9c (40 mg, 0.07 mmol, 1 equiv) and 1-adamantanemethanol (O; 22 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 33 mg (67%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.67–7.48 (m, 2 H), 7.34 (m, 15 H), 5.57 (s, 1 H), 5.04 (d, J = 11.4 Hz, 1 H), 4.93 (d, J = 11.3 Hz, 1 H), 4.86 (d, J = 11.3 Hz, 1 H), 4.79 (d, J = 12.0 Hz, 1 H), 4.75–4.69 (m, 1 H), 4.69–4.60 (m, 1 H), 4.27 (dd, J = 10.0, 4.6 Hz, 1 H), 4.05 (t, J = 9.2 Hz, 1 H), 3.82 (dd, J = 9.2, 5.2 Hz, 1 H), 3.76–3.67 (m, 1 H), 3.67–3.48 (m, 1 H), 3.28 (t, J = 7.0 Hz, 3 H), 2.88 (dd, J = 17.2, 9.1 Hz, 1 H), 1.98 (s, 3 H), 1.76–1.54 (m, 19 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.5, 137.4, 129.7, 128.9, 128.8, 128.5, 128.4, 128.3, 128.2, 128.2, 127.9, 127.8, 127.7, 127.6, 127.4, 125.7, 101.1, 98.4, 97.1, 82.3, 80.3, 79.2, 78.4, 75.2, 72.9, 69.2, 62.7, 62.3, 39.6, 37.1, 33.8, 28.2.

2,3,4,6-Tetra-O-benzyl-α-d-mannopyranosyl)-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (14a)

Product 14a was isolated from the reaction between 9d (45 mg, 0.07 mmol, 1 equiv) and A (19 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 53 mg (69%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.39–7.26 (m, 19 H), 7.15 (dd, J = 7.2, 2.2 Hz, 2 H), 5.53 (d, J = 5.0 Hz, 1 H), 5.03 (d, J = 1.6 Hz, 1 H), 4.87 (d, J = 10.7 Hz, 1 H), 4.77–4.73 (m, 2 H), 4.70–4.65 (m, 2 H), 4.60 (dd, J = 8.0, 2.3 Hz, 1 H), 4.58 (d, J = 3.2 Hz, 2 H), 4.51 (dd, J = 15.4, 11.5 Hz, 3 H), 4.32 (dd, J = 5.0, 2.4 Hz, 1 H), 4.16 (dd, J = 7.9, 1.8 Hz, 1 H), 4.05–3.89 (m, 3 H), 3.85–3.75 (m, 5 H), 3.75–3.67 (m, 2 H), 1.50 (s, 3 H), 1.43 (s, 3 H), 1.33 (s, 9 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.5, 138.4, 138.3, 128.4, 128.3, 128.0, 127.8, 127.6, 127.5, 127.4, 109.3, 108.5, 97.1, 96.3, 80.0, 75.1, 74.8, 74.4, 73.3, 72.3, 72.0, 70.8, 70.6, 70.5, 69.0, 65.3, 65.2, 26.1, 25.9, 24.9, 24.5.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-mannopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (14b)

Product 14b was isolated from the reaction between 9d (67 mg, 0.1 mmol, 1 equiv) and B (55 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 70 mg (74%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.40–7.27 (m, 27 H), 7.25–7.20 (m, 6 H), 7.14 (dd, J = 6.7, 2.8 Hz, 2 H), 4.99 (t, J = 6.3 Hz, 2 H), 4.88 (dd, J = 11.0, 6.7 Hz, 2 H), 4.80 (dd, J = 11.5, 5.1 Hz, 2 H), 4.74–4.70 (m, 2 H), 4.66 (dd, J = 13.4, 5.4 Hz, 1 H), 4.62 (d, J = 2.3 Hz, 1 H), 4.60 (d, J = 6.4 Hz, 1 H), 4.58–4.55 (m, 2 H), 4.51 (t, J = 4.1 Hz, 2 H), 4.49–4.42 (m, 2 H), 3.99 (q, J = 9.6 Hz, 2 H), 3.88–3.82 (m, 2 H), 3.81–3.78 (m, 1 H), 3.74–3.57 (m, 6 H), 3.46 (dd, J = 9.6, 3.5 Hz, 1 H), 3.43–3.33 (m, 2 H), 3.31 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.6, 138.4, 138.1, 128.5, 128.4, 128.3, 128.2, 128.0, 127.8, 127.7, 127.6, 127.5, 127.4, 98.2, 97.8, 82.1, 80.0, 79.5, 77.6, 75.8, 75.0, 74.9, 74.8, 74.5, 73.2, 72.4, 72.0, 71.9, 69.7, 69.0, 65.7, 55.1.

HRMS (ESI/Q-TOF): m/z [M + H]⁺ calcd for C₆₂H₆₆O₁₁: 1009.4497; found: 1009.4451.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-mannopyranosyl)-(1→6)-2,3,4-tri-O-benzyl-1-thio-β-d-glucopyranoside (14c)

Product 14c was isolated from the reaction between 9d (67 mg, 0.1 mmol, 1 equiv) and D (65 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 67 mg (65%, α only); colorless sticky liquid; R_f = 0.45 (EtOAc­/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.53 (d, J = 7.2 Hz, 2 H), 7.42 (d, J = 6.8 Hz, 4 H), 7.39–7.27 (m, 22 H), 7.25–7.11 (m, 13 H), 5.05 (s, 1 H), 4.96–4.89 (m, 3 H), 4.87–4.82 (m, 1 H), 4.80–4.75 (m, 3 H), 4.68–4.56 (m, 5 H), 4.54–4.42 (m, 3 H), 4.02 (t, J = 9.4 Hz, 1 H), 3.93–3.83 (m, 3 H), 3.81–3.60 (m, 5 H), 3.50–3.35 (m, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.6, 138.4, 138.3, 138.2, 137.8, 133.5, 132.1, 129.4, 129.0, 128.5, 128.4 ,128.3, 128.2, 127.8, 127.7, 126.3, 100.5, 98.4, 87.7, 86.6, 81.0, 79.6, 78.3, 75.9, 75.5, 75.0, 74.7, 74.3, 73.2, 72.2, 71.9, 71.8, 69.0, 66.2.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₆₇H₆₈O₁₀S: 1087.4425; found: 1087.4420.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-mannopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-β-d-glucopyranoside (14d)

Product 14d was isolated from the reaction between 9d (52 mg, 0.07 mmol, 1 equiv) and E (47 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 38 mg (53%, α only); colorless semisolid; R_f = 0.4 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.99–7.94 (m, 2 H), 7.85 (d, J = 7.3 Hz, 2 H), 7.81–7.77 (m, 2 H), 7.57–7.27 (m, 23 H), 7.25–7.20 (m, 9 H), 7.14 (dd, J = 6.9, 2.4 Hz, 2 H), 5.84 (t, J = 9.6 Hz, 1 H), 5.51 (t, J = 9.7 Hz, 1 H), 5.44 (t, J = 9.7 Hz, 1 H), 4.96 (d, J = 10.0 Hz, 1 H), 4.92 (d, J = 1.3 Hz, 1 H), 4.85 (d, J = 10.9 Hz, 1 H), 4.68 (s, 2 H), 4.58 (d, J = 12.1 Hz, 1 H), 4.48–4.36 (m, 4 H), 3.96–3.89 (m, 3 H), 3.81 (dd, J = 9.4, 3.1 Hz, 1 H), 3.70–3.57 (m, 5 H).

¹³C NMR (125 MHz, CDCl₃): δ = 165.8, 165.1, 164.9, 138.6, 138.4, 138.3, 133.3, 133.2, 133.1, 131.8, 129.9, 129.7, 129.2, 129.0, 128.8, 128.4, 128.3, 128.2, 127.9, 98.3, 86.4, 80.0, 75.0, 74.6, 74.5, 74.1, 73.2, 72.5, 72.0, 71.8, 70.5, 69.8, 69.0, 66.7.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-mannopyranosyl-(1→4)-2,3,6-tri-O-benzyl-α-d-glucopyranoside (14e)

Product 14e was isolated from the reaction between 9d (50 mg, 0.07 mmol, 1 equiv) and B (33 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 43 mg (67%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.34–7.25 (m, 20 H), 7.25–7.13 (m, 11 H), 5.30 (d, J = 1.8 Hz, 1 H), 5.09 (d, J = 11.7 Hz, 1 H), 4.85 (d, J = 10.8 Hz, 1 H), 4.68 (d, J = 12.1 Hz, 1 H), 4.62–4.55 (m, 7 H), 4.53–4.47 (m, 1 H), 4.43 (dd, J = 12.0, 2.2 Hz, 2 H), 4.31 (d, J = 12.1 Hz, 1 H), 4.21 (d, J = 12.1 Hz, 1 H), 3.98 (t, J = 9.4 Hz, 1 H), 3.87 (dd, J = 9.2, 2.7 Hz, 1 H), 3.84–3.76 (m, 2 H), 3.75–3.69 (m, 5 H), 3.67 (dd, J = 10.8, 4.7 Hz, 1 H), 3.60–3.51 (m, 2 H), 3.40 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.6, 138.5, 138.3, 137.8, 128.4, 128.3, 128.2, 128.1, 128.0, 127.7, 127.6, 127.5, 127.4, 127.1, 126.7, 100.5, 97.6, 81.5, 79.9, 77.7, 76.2, 75.0, 74.8, 73.3, 73.2, 73.1, 72.9, 72.2, 69.7, 69.3, 55.2.

Methyl 2,3,4,6-Tetra-O-benzyl-α/β-d-mannopyranosyl-(1→3)-2-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (14f)

Product 14f was isolated from the reaction between 9d (50 mg, 0.07 mmol, 1 equiv) and G (55 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 43 mg (66%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.41–7.25 (m, 27 H), 7.15 (d, J = 7.2 Hz, 1 H), 7.09 (t, J = 7.3 Hz, 2 H), 7.02 (d, J = 7.2 Hz, 2 H), 5.62 (d, J = 3.5 Hz, 1 H), 5.44 (s, 1 H), 4.87 (dd, J = 14.7, 11.6 Hz, 2 H), 4.76–4.69 (m, 3 H), 4.60–4.51 (m, 4 H), 4.46–4.43 (m, 1 H), 4.40–4.34 (m, 4 H), 4.30–4.18 (m, 2 H), 4.01–3.92 (m, 3 H), 3.89–3.79 (m, 2 H), 3.77–3.50 (m, 6 H), 3.34 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.9, 138.8, 138.3, 138.0, 137.0, 129.2, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.4, 127.3, 127.2, 126.2, 101.8, 98.7, 96.7, 83.0, 78.3, 78.2, 75.2, 74.9, 73.4, 73.0, 72.9, 72.3, 71.6, 69.1, 68.7, 68.4, 61.8, 55.2.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₅₅H₅₈O₁₁: 917.3871; found: 917.3828.

1-Adamantanol 2,3,4,6-Tetra-O-benzyl-α-d-mannopyranoside (14g)

Product 14g was isolated from the reaction between 9d (51 mg, 0.07 mmol, 1 equiv) and 1-adamantanol (J; 14 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 30 mg (63%, α only); semi-solid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (500 MHz, CDCl₃): δ = 7.40–7.26 (m, 16 H), 7.24 (dd, J = 9.1, 2.2 Hz, 2 H), 7.18–7.15 (m, 2 H), 5.25 (d, J = 1.8 Hz, 1 H), 4.88 (d, J = 10.6 Hz, 1 H), 4.76 (d, J = 12.5 Hz, 1 H), 4.73–4.68 (m, 2 H), 4.62 (d, J = 3.3 Hz, 2 H), 4.50 (dd, J = 11.2, 9.1 Hz, 2 H), 4.03–3.94 (m, 3 H), 3.81 (dd, J = 10.6, 3.8 Hz, 1 H), 3.71 (d, J = 10.5 Hz, 1 H), 3.59 (t, J = 2.0 Hz, 3 H), 2.08 (s), 1.72 (d, J = 13.4 Hz, 6 H), 1.57 (dd, J = 26.7, 10.5 Hz, 9 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.7, 138.5, 128.3, 128.2, 128.0, 127.7, 127.6, 127.5, 127.3, 90.9, 80.2, 75.8, 75.2, 74.4, 73.2, 72.3, 72.0, 71.2, 69.4, 68.8, 42.2, 36.2, 30.5.

(+)-Menthol 2,3,4,6-Tetra-O-benzyl-α-d-mannopyranoside (14h)

Product 14h was isolated from the reaction between 9d (50 mg, 0.07 mmol, 1 equiv) and (+)-menthol (K; 13 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 38 mg (78%, α only); sticky liquid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.43–7.27 (m, 17 H), 7.26 (s, 1 H), 7.16 (dd, J = 6.7, 2.6 Hz, 2 H), 5.01 (d, J = 1.0 Hz, 1 H), 4.84 (dd, J = 20.9, 11.6 Hz, 2 H), 4.69 (dd, J = 12.8, 3.6 Hz, 4 H), 4.52 (dd, J = 11.5, 2.6 Hz, 2 H), 4.05 (d, J = 9.5 Hz, 1 H), 3.91–3.76 (m, 3 H), 3.73–3.65 (m, 2 H), 3.43 (td, J = 10.6, 4.0 Hz, 1 H), 2.20–2.09 (m, 1 H), 1.82 (d, J = 11.8 Hz, 1 H), 1.61 (d, J = 10.5 Hz, 2 H), 1.16 (dd, J = 20.0, 9.4 Hz, 1 H), 1.01–0.79 (m, 9 H), 0.73 (d, J = 6.9 Hz, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.6, 138.4, 128.3, 128.2, 128.0, 127.7, 127.6, 127.4, 94.5, 80.2, 75.7, 75.3, 75.2, 74.2, 73.4, 72.8, 72.3, 72.1, 69.1, 47.8, 39.6, 34.4, 31.2, 25.1, 22.7, 22.2, 21.1, 15.3.

(–)-Menthol 2,3,4,6-Tetra-O-benzyl-α-d-mannopyranoside (14i)

Product 14i was isolated from the reaction between 9d (67 mg, 0.1 mmol, 1 equiv) and (–)-menthol (L; 18 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 50 mg (72%, α only); sticky liquid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (400 MHz, CDCl₃): δ = 7.38–7.25 (m, 18 H), 7.19–7.15 (m, 2 H), 4.90 (d, J = 10.7 Hz, 1 H), 4.86 (d, J = 1.3 Hz, 1 H), 4.75–4.70 (m, 2 H), 4.67 (d, J = 7.2 Hz, 1 H), 4.65–4.60 (m, 2 H), 4.51 (dd, J = 13.4, 11.5 Hz, 2 H), 3.96–3.86 (m, 3 H), 3.79 (dd, J = 10.5, 4.4 Hz, 1 H), 3.76–3.66 (m, 2 H), 3.24 (td, J = 10.6, 4.3 Hz, 1 H), 2.13 (d, J = 11.8 Hz, 1 H), 1.76 (dq, J = 6.8, 4.7 Hz, 1 H), 1.60–1.53 (m, 2 H), 1.10 (dd, J = 15.4, 6.8 Hz, 1 H), 0.99–0.88 (m, 3 H), 0.82 (dd, J = 6.7, 3.1 Hz, 6 H), 0.63 (d, J = 6.9 Hz, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.5, 138.4, 138.2, 128.3, 128.2, 128.0, 127.9, 127.7, 127.6, 127.5, 127.4, 99.8, 81.0, 80.0, 75.2, 75.1, 74.33, 73.2, 72.3, 72.2, 71.7, 69.4, 48.6, 42.8, 34.2, 31.5, 25.7, 23.2, 22.1, 21.0, 16.2.

Cholesteryl 2,3,4,6-Tetra-O-benzyl-α/β-d-mannopyranoside (14j)

Product 14j was isolated from the reaction between 9d (67 mg, 0.1 mmol, 1 equiv) and cholesterol (N; 46 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 58 mg (65%, α only); white solid; R_f = 0.40 (EtOAc/hexane 1:10); mp 124–127 °C.

¹H NMR (500 MHz, CDCl₃): δ = 7.40–7.27 (m, 17 H), 7.20–7.14 (m, 2 H), 5.28 (d, J = 5.0 Hz, 1 H), 5.04 (s, 1 H), 4.88 (d, J = 10.6 Hz, 1 H), 4.74 (d, J = 7.5 Hz, 2 H), 4.71–4.63 (m, 3 H), 4.52 (dd, J = 11.3, 8.2 Hz, 2 H), 3.97 (dt, J = 12.2, 9.3 Hz, 2 H), 3.88–3.73 (m, 4 H), 3.52–3.43 (m, 1 H), 2.37–2.21 (m, 2 H), 2.05–1.76 (m, 6 H), 1.54–1.23 (m, 13 H), 1.11 (dd, J = 19.2, 13.2 Hz, 8 H), 0.98 (d, J = 5.7 Hz, 5 H), 0.92 (d, J = 6.5 Hz, 4 H), 0.87 (dd, J = 6.6, 1.7 Hz, 7 H).

¹³C NMR (125 MHz, CDCl₃): δ = 140.6, 138.6, 138.4, 128.3, 128.2, 128.1, 127.8, 127.6, 127.5, 127.4, 121.8, 95.7, 80.3, 76.4, 75.2, 75.1, 73.3, 72.5, 72.1, 71.7, 69.3, 56.7, 56.1, 50.0, 42.3, 39.8, 39.7, 39.5, 37.0, 36.6, 36.2, 35.8, 31.9, 31.8, 28.2, 28.0, 27.6, 24.3, 23.8, 22.8, 22.6, 21.0, 19.3, 18.7, 11.8.

HRMS (ESI/Q-TOF): m/z [M + NH₄]⁺ calcd for C₆₁H₈₀O₆: 926.6299; found: 926.6297.

2,3,4-Tri-O-benzyl-α/β-d-galactopyranosyl-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (15a)

Product 15a was isolated from the reaction between 9e (67 mg, 0.1 mmol, 1 equiv) and A (31 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 59 mg (76%, α/β = 1.2:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.54 (dd, J = 7.3, 2.4 Hz, 1 H), 7.45 (dd, J = 7.6, 1.6 Hz, 2 H), 7.41–7.26 (m, 33 H), 5.56 (d, J = 5.0 Hz, 1 H), 5.51 (d, J = 5.0 Hz, 0.85 H), 5.05 (d, J = 11.0 Hz, 1 H), 5.01 (d, J = 3.6 Hz, 1 H), 4.93 (dd, J = 11.5, 2.5 Hz, 2 H), 4.82 (t, J = 8.6 Hz, 1 H), 4.73 (dt, J = 11.9, 9.3 Hz, 5 H), 4.64–4.55 (m, 4 H), 4.49–4.36 (m, 5 H), 4.33–4.29 (m, 3 H), 4.22 (dd, J = 7.9, 1.8 Hz, 1 H), 4.12 (d, J = 10.5 Hz, 1 H), 4.09–3.92 (m, 6 H), 3.88 (d, J = 2.7 Hz, 1 H), 3.86–3.65 (m, 4 H), 3.60–3.48 (m, 6 H), 1.50 (d, J = 11.5 Hz, 6 H), 1.43 (d, J = 2.7 Hz, 6 H), 1.31 (t, J = 4.9 Hz, 12 H).

¹³C NMR (100 MHz, CDCl₃): δ = 139.0, 138.9, 138.7, 138.6, 131.6, 128.4, 128.3, 128.2, 128.1, 127.9, 127.8, 127.7, 127.5, 109.3, 109.2, 108.6, 108.5, 104.6, 97.5, 96.3, 81.9, 79.1, 78.9, 76.3, 74.8, 74.7, 74.5, 73.5, 73.4, 73.2, 73.1, 73.0, 72.7, 71.4, 70.8, 70.7, 70.6, 70.4, 69.6, 69.1, 68.6, 67.3, 66.3, 65.8, 26.1, 26.0, 25.9, 25.0, 24.9, 24.6, 24.4.

Methyl 2,3,4,6-Tetra-O-benzyl-α-d-galactopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (15b)

Product 15b was isolated from the reaction between 9e (67 mg, 0.1 mmol, 1 equiv) and B (55 mg, 0.12 mmol, 1.2 equiv) by following GP-2.

Yield: 68 mg (70%, α/β = 1.6:1); semi-solid.

¹H NMR (400 MHz, CDCl₃): δ = 7.39–7.26 (m, 59 H), 7.25–7.15 (m, 15 H), 5.01–4.91 (m, 6 H), 4.75 (m, 16 H), 4.61–4.51 (m, 8 H), 4.50–4.29 (m, 7 H), 4.17–4.09 (m, 2 H), 4.06–3.89 (m, 9 H), 3.87–3.67 (m, 7 H), 3.65–3.38 (m, 13 H), 3.30 (s, 1.9 H), 3.29 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.7, 138.6, 138.3, 138.1, 138.0, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 104.1, 97.9, 97.8, 82.2, 82.0, 80.1, 79.7, 79.2, 78.2, 78.0, 76.8, 75.7, 75.0, 74.7, 73.5, 73.3, 72.8, 72.5, 70.2, 69.8, 69.3, 68.8, 68.5, 66.4, 55.1, 55.0.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-galactopyranosyl)-(1→6)-2,3,4-tri-O-benzyl-1-thio-β-d-glucopyranoside (15c)

Product 15c was isolated from the reaction between 9e (50 mg, 0.07 mmol, 1 equiv) and D (46 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 53 mg (72%, α/β = 1.35:1); colorless sticky liquid; R_f = 0.45 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.53 (dd, J = 8.3, 1.2 Hz, 2 H), 7.43–7.26 (m, 48 H), 7.26–7.15 (m, 9 H), 5.04 (d, J = 3.5 Hz, 1 H), 4.96 (d, J = 11.4 Hz., 1 H), 4.90–4.84 (m, 3 H), 4.83 (d, J = 9.3 Hz, 2 H), 4.82–4.77 (m, 2 H), 4.73 (d, J = 11.9 Hz, 2 H), 4.67 (d, J = 9.9 Hz, 1 H), 4.63 (d, J = 5.7 Hz, 1 H), 4.62–4.59 (m, 2 H), 4.57 (d, J = 1.8 Hz, 1 H), 4.55–4.50 (m, 1 H), 4.49–4.39 (m, 3 H), 4.09–4.04 (m, 1 H), 4.00 (t, J = 6.5 Hz, 1 H), 3.92–3.85 (m, 3 H), 3.79 (dt, J = 11.6, 8.1 Hz, 3 H), 3.65 (dt, J = 18.5, 9.1 Hz, 3 H), 3.58–3.50 (m, 4 H), 3.27 (dd, J = 9.8, 8.5 Hz, 1 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.9, 138.7, 138.5, 138.1, 138.0, 134.0, 131.7, 128.9, 128.4, 128.3, 128.2, 127.8, 127.7, 127.6, 127.4, 100.2, 97.7, 87.5, 86.6, 81.0, 78.7, 78.3, 77.8, 76.3, 75.6, 75.5, 75.1, 75.0, 74.8, 74.1, 73.2, 73.0, 72.7, 72.6, 72.1, 71.1, 69.0, 68.9, 66.2, 64.3.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₆₇H₆₈O₁₀S: 1087.4425; found: 1087.4460.

Phenyl-O-(2,3,4,6-tetra-O-benzyl-α/β-d-galactopyranosyl)-(1→6)-2,3,4-tri-O-benzoyl-1-thio-β-d-glucopyranoside (15d)

Product 15d was isolated from the reaction between 9e (53 mg, 0.07 mmol, 1 equiv) and E (54 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 58 mg (68%, α only); R_f = 0.4 (EtOAc/hexane 1:4); colorless semi-solid.

¹H NMR (500 MHz, CDCl₃): δ = 7.99–7.94 (m, 2 H), 7.94–7.86 (m, 2 H), 7.80–7.77 (m, 2 H), 7.55–7.26 (m, 31 H), 7.25–7.15 (m, 9 H), 5.87 (t, J = 9.5 Hz, 1 H), 5.45 (dt, J = 13.2, 9.8 Hz, 2 H), 5.05 (dd, J = 10.1, 5.6 Hz, 1 H), 4.95 (d, J = 5.8 Hz, 0.15 H), 4.91 (d, J = 11.4 Hz, 1 H), 4.80 (dd, J = 11.9, 9.2 Hz, 2 H), 4.75–4.61 (m, 3 H), 4.57–4.49 (m, 1 H), 4.46–4.36 (m, 2 H), 4.16–4.10 (m, 1 H), 4.07–4.01 (m, 2 H), 3.92–3.85 (m, 3 H), 3.56–3.43 (m, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 165.7, 165.1, 139.0, 138.6, 138.5, 138.2, 133.5, 133.3, 133.2, 132.8, 132.0, 129.9, 129.8, 129.7, 129.0, 128.8, 128.4, 128.3, 128.2, 128.1, 127.7, 127.6, 127.5, 127.4, 127.2, 104.2, 97.7, 86.1, 78.9, 75.0, 74.8, 74.3, 73.6, 73.1, 70.5, 68.9, 68.7, 67.0.

Methyl 2,3,4,6-Tetra-O-benzyl-α-d-galactopyranosyl-(1→3)-2-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside (15e)

Product 15e was isolated from the reaction between 9e (50 mg, 0.07 mmol, 1 equiv) and G (33 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 45 mg (69%, α only); colorless sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.41–7.27 (m, 20 H), 7.23–7.01 (m, 10 H), 5.62 (d, J = 3.5 Hz, 1 H), 5.44 (s, 1 H), 4.87 (dd, J = 14.8, 11.6 Hz, 2 H), 4.73 (dd, J = 11.8, 10.0 Hz, 2 H), 4.55 (m, 4 H), 4.46–4.30 (m, 5 H), 4.22 (dd, J = 10.1, 4.7 Hz, 1 H), 4.02–3.90 (m, 3 H), 3.89–3.79 (m, 1 H), 3.78–3.67 (m, 2 H), 3.65–3.50 (m, 3 H), 3.34 (s, 3 H).

¹³C NMR (100 MHz, CDCl₃): δ = 138.9, 138.8, 138.4, 138.3, 138.0, 137.0, 129.2, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.4, 127.3, 127.2, 126.2, 101.8, 98.7, 96.7, 83.0, 78.3, 78.2, 75.7, 75.2, 74.9, 73.4, 73.0, 72.9, 72.3, 71.6, 69.1, 68.7, 68.4, 61.8, 55.2.

(±)-Menthol 2,3,4,6-Tetra-O-benzyl-α-d-galactopyranoside (15f)

Product 15f was isolated from the reaction between 9e (50 mg, 0.07 mmol, 1 equiv) and (±)-menthol (M; 14 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 38 mg (75%, α(+)/α(–)/β = 3:3:1); colorless liquid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (500 MHz, CDCl₃): δ = 7.41–7.27 (m, 51 H), 5.03 (d, J = 3.8 Hz, 2 H), 4.98–4.92 (m, 3 H), 4.85 (d, J = 9.7 Hz, 1 H), 4.83 (d, J = 2.7 Hz, 1 H), 4.82–4.80 (m, 1 H), 4.78–4.71 (m, 4 H), 4.69 (dd, J = 7.9, 3.8 Hz, 2 H), 4.65 (d, J = 7.5 Hz, 1 H), 4.63–4.57 (m, 2 H), 4.49 (d, J = 11.9 Hz, 1 H), 4.44 (t, J = 5.8 Hz, 1 H), 4.42–4.37 (m, 4 H), 4.12 (dd, J = 7.0, 6.2 Hz, 1 H), 4.07 (d, J = 3.8 Hz, 1 H), 4.05 (dd, J = 5.7, 3.8 Hz, 1 H), 4.03–4.00 (m, 3 H), 3.96 (m, 2 H), 3.87–3.85 (m, 0.5 H), 3.76 (dd, J = 9.8, 7.7 Hz, 0.3 H), 3.59–3.49 (m, 5 H), 3.47–3.40 (m, 3 H), 3.34 (td, J = 10.7, 4.4 Hz, 1 H), 2.46–2.38 (m, 1 H), 2.26–2.20 (m, 1 H), 2.13 (d, J = 12.6 Hz, 0.3 H), 2.08 (d, J = 12.0 Hz, 1 H), 2.00 (d, J = 11.7 Hz, 1 H), 1.69–1.57 (m, 8 H), 1.43 (t, J = 11.3 Hz, 1 H), 1.37–1.23 (m, 7 H), 1.03 (d, J = 11.0 Hz, 1 H), 0.94 (d, J = 6.5 Hz, 7 H), 0.93–0.87 (m, 9 H), 0.83 (dd, J = 6.8, 5.1 Hz, 9 H), 0.76 (d, J = 6.8 Hz, 2 H), 0.70 (dd, J = 9.4, 7.0 Hz, 7 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.9, 138.8, 138.7, 138.6, 138.1, 137.9, 128.4, 128.3, 128.2, 128.1, 127.9, 127.7, 127.6, 127.5, 127.4, 127.3, 101.6, 99.3, 93.8, 82.6, 80.1, 79.5, 79.2, 78.4, , 76.4, 75.2, 75.1, 75.0, 74.8, 74.6, 74.4, 73.8, 73.7, 73.6, 73.5, 73.4, 73.2, 73.0, 72.6, 69.3, 69.2, 69.1, 68.4, 48.8, 48.0, 47.3, 42.8, 41.2, 39.6, 34.4, 34.2, 31.7, 31.5, 31.3, 25.3, 24.8, 24.4, 23.0, 22.8, 22.7, 22.4, 22.3, 22.2, 21.1, 16.0, 15.6, 15.1.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₄₄H₅₄O₆: 701.3813; found: 701.3848.

Cholesteryl 2,3,4,6-Tetra-O-benzyl-α/β-d-galactopyranoside (15g)

Product 15g was isolated from the reaction between 9e (53 mg, 0.08 mmol, 1 equiv) and cholesterol (N; 54 mg, 0.09 mmol, 1.2 equiv) by following GP-2.

Yield: 58 mg (68%, α/β = 3.2:1); white solid; R_f = 0.40 (EtOAc/hexane 1:10); mp 127–131 °C.

¹H NMR (500 MHz, CDCl₃): δ = 7.41–7.26 (m, 27 H), 5.32 (dd, J = 3.3, 2.0 Hz, 0.31 H), 5.26 (dd, J = 3.4, 1.8 Hz, 1 H), 5.00–4.92 (m, 3 H), 4.86 (d, J = 11.6 Hz, 1 H), 4.80 (d, J = 12.0 Hz, 1 H), 4.78–4.71 (m, 2 H), 4.68 (d, J = 12.1 Hz, 1 H), 4.64–4.57 (m, 1 H), 4.44 (dt, J = 15.3, 11.6 Hz, 3 H), 4.08–3.94 (m, 4 H), 3.87 (d, J = 2.8 Hz, 0.3 H), 3.80 (dd, J = 9.7, 7.7 Hz, 0.3 H), 3.58–3.44 (m, 5 H), 2.47–2.38 (m, 1 H), 2.30–2.26 (m, 1 H), 2.04–1.80 (m, 7 H), 1.54–1.41 (m, 7 H), 1.39–1.24 (m, 6 H), 1.21–1.06 (m, 8 H), 1.01 (d, J = 2.1 Hz, 8 H), 0.92 (d, J = 6.5 Hz, 6 H), 0.87 (dd, J = 6.6, 2.3 Hz, 9 H), 0.68 (s, 4 H).

¹³C NMR (125 MHz, CDCl₃): δ = 140.9, 138.9, 138.7, 138.6, 138.0, 128.4, 128.3, 128.2, 128.1, 128.0, 127.7, 127.6, 127.5, 127.4, 121.6, 102.4, 95.4, 79.4, 79.2, 76.6, 76.4, 75.3, 75.1, 74.7, 74.4, 73.5, 73.4, 73.2, 73.1, 69.1, 69.0, 56.7, 56.1, 50.1, 42.3, 39.8, 39.7, 39.5, 37.1, 36.7, 36.2, 35.8, 31.9, 31.8, 28.2, 28.0, 27.6, 24.3, 23.8, 22.8, 22.6, 21.0, 19.4, 18.7, 11.8.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₆₁H₈₀O₆: 931.5847; found: 931.5853.

Methyl 2,3,4-Tri-O-benzyl-α-l-rhamanopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (16a)

Product 16a was isolated from the reaction between 9f (40 mg, 0.07 mmol, 1 equiv) and B (40 mg, 0.085 mmol, 1.2 equiv) by following GP-2.

Yield: 46 mg (76%, α only); yellow liquid; R_f = 0.40 (EtOAc/hexane 1:10).

¹H NMR (500 MHz, CDCl₃): δ = 7.39–7.27 (m, 25 H), 7.25–7.19 (m, 5 H), 4.97 (dd, J = 14.9, 10.8 Hz, 2 H), 4.80 (d, J = 2.6 Hz, 1 H), 4.78 (d, J = 2.0 Hz, 1 H), 4.72 (dd, J = 7.1, 5.4 Hz, 2 H), 4.68 (d, J = 5.1 Hz, 1 H), 4.66 (d, J = 4.0 Hz, 1 H), 4.62 (d, J = 13.2 Hz, 2 H), 4.53 (d, J = 3.5 Hz, 1 H), 4.37 (d, J = 11.0 Hz, 1 H), 3.94 (d, J = 9.2 Hz, 1 H), 3.86–3.80 (m, 2 H), 3.73–3.66 (m, 3 H), 3.63 (d, J = 9.4 Hz, 1 H), 3.47 (dd, J = 9.6, 3.5 Hz, 1 H), 3.44 (dd, J = 10.8, 5.6 Hz, 1 H), 3.37–3.32 (m, 1 H), 3.27 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.7, 138.5, 138.2, 138.0, 128.5, 128.4, 128.3, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 98.2, 97.7, 81.9, 80.5, 79.9, 79.7, 77.8, 75.8, 75.5, 75.0, 74.8, 73.3, 72.7, 72.3, 69.8, 68.0, 66.0, 55.0, 17.9.

(2,3,4-Tri-O-benzyl-α-l-rhamanopyranosyl-(1→6)-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (16b)

Product 16b was isolated from the reaction between 9f (40 mg, 0.07 mmol, 1 equiv) and A (22 mg, 0.08 mmol, 1.2 equiv) by following GP-2.

Yield: 33 mg (67%, α only); yellow liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.40–7.27 (m, 15 H), 5.52 (d, J = 5.0 Hz, 1 H), 4.95 (d, J = 10.9 Hz, 1 H), 4.89 (d, J = 1.6 Hz, 1 H), 4.73 (s, 2 H), 4.64 (d, J = 10.9 Hz, 1 H), 4.60–4.56 (m, 3 H), 4.30 (dd, J = 5.0, 2.4 Hz, 1 H), 4.15 (dd, J = 8.0, 1.9 Hz, 1 H), 3.91–3.88 (m, 1 H), 3.86–3.78 (m, 3 H), 3.77–3.72 (m, 1 H), 3.62 (t, J = 9.3 Hz, 1 H), 3.55 (dd, J = 10.5, 7.0 Hz, 1 H), 1.51 (s, 3 H), 1.43 (s, 3 H), 1.33 (s, 5 H), 1.32 (d, J = 2.5 Hz, 4 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.7, 138.5, 138.4, 128.3, 127.9, 127.6, 127.4, 109.3, 108.5, 98.0, 96.2, 80.4, 79.9, 75.2, 74.6, 72.6, 71.9, 71.1, 70.5, 68.0, 67.2, 65.9, 26.1, 25.9, 24.9, 24.4, 17.9.

Methyl-2,3,4,6-tetra-O-benzyl-α/β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzoyl-β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranoside (17)

Product 17 was isolated from the reaction between 15d (40 mg, 0.04 mmol, 1 equiv) and B (23 mg, 0.05 mmol, 1.2 equiv) by following a literature procedure.[28]

Yield: 27 mg (52%, β only); R_f = 0.5 (EtOAc/hexane 1:4); sticky liquid.

¹H NMR (500 MHz, CDCl₃): δ = 8.08–7.78 (m, 9 H), 7.55–7.29 (m, 20 H), 7.26–7.10 (m, 20 H), 5.85 (t, J = 9.4 Hz, 1 H), 5.70 (t, J = 9.6 Hz, 1 H), 5.60–5.44 (m, 1 H), 5.34 (d, J = 3.5 Hz, 1 H), 4.94–4.74 (m, 6 H), 4.72–4.35 (m, 10 H), 4.33–4.15 (m, 1 H), 4.08–3.56 (m, 10 H), 3.48 (dd, J = 11.5, 8.6 Hz, 2 H), 3.33 (d, J = 3.7 Hz, 1 H), 3.19 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 165.9, 165.8, 165.0, 138.2, 133.1, 132.9, 129.7, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.7, 127.6, 127.5, 127.4, 127.3, 126.8, 126.6, 101.2, 101.0, 97.9, 97.3, 81.5, 81.0, 79.9, 79.6, 76.3, 75.4, 74.9, 74.5, 74.4, 73.3, 73.1, 73.0, 72.7, 71.9, 71.8, 71.3, 54.9.

2,3,4-Tri-O-benzyl-α-d-glucopyranosyl Phenylpropiolate (19)

Product 19 was isolated by a silyl deprotection reaction of 9d (100 mg, 0.12 mmol, 1 equiv) by following a literature procedure.[22]

Yield: 36 mg (51%, α only); sticky liquid; R_f = 0.5 (EtOAc/hexane 2:3).

¹H NMR (500 MHz, CDCl₃): δ = 7.64–7.58 (m, 3 H), 7.47 (d, J = 7.5 Hz, 2 H), 7.42–7.28 (m, 30 H), 6.34 (d, J = 3.5 Hz, 1 H), 5.04–4.96 (m, 1 H), 4.94–4.85 (m, 3 H), 4.76–4.63 (m 4 H), 4.10–4.01 (m, 2 H), 3.90–3.82 (m, 2 H), 3.77–3.57 (m, 5 H).

¹³C NMR (125 MHz, CDCl₃): δ = 152.5, 138.5, 138.5, 138.5, 138.4, 137.8, 137.7, 137.6, 137.3, 137.3, 134.7, 133.1, 133.2, 133.03, 130.9, 128.5, 128.4, 128.2, 128.1, 128.0, 127.8, 127.7, 119.3, 91.3, 88.1, 81.4, 80.1, 78.7, 76.4, 75.7, 75.3, 73.6, 73.5, 61.3.

HRMS (ESI/Q-TOF): m/z [M + Na]⁺ calcd for C₃₆H₃₄O₇: 601.2197; found: 601.2177.

2,3,4,6-Tetra-O-benzyl-β-d-glucopyranosyl-(1→6)-2,3,4-tri-O-benzyl-α-d-glucopyranosyl phenylpropiolate (20)

Product 20 was isolated from the reaction between phenyl-2,3,4,6-tetra-O-benzyl-β-d-thioglucopyranoside (44 mg, 0.07 mmol, 1 equiv) and 2,3,4-tri-O-benzyl-α-d-glucopyranosyl phenylpropiolate (19; 32 mg, 0.08 mmol, 1.2 equiv) by following a literature procedure.[28]

Yield: 44 mg (57%, α only); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (400 MHz, CDCl₃): δ = 7.63–7.57 (m, 2 H), 7.46 (d, J = 7.5 Hz, 3 H), 7.41–7.27 (m, 38 H), 7.19–7.14 (m, 7 H), 6.45 (d, J = 3.4 Hz, 1 H), 5.00–4.89 (m, 5 H), 4.85–4.77 (m, 5 H), 4.75–4.66 (m, 5 H), 4.63–4.50 (m, 6 H), 4.35 (d, J = 7.8 Hz, 2 H), 4.27–4.01 (m, 5 H), 3.65 (m, 6 H).

¹³C NMR (100 MHz, CDCl₃): δ = 152.4, 138.6, 138.4, 138.2, 138.1, 138.0, 137.4, 133.1, 132.9, 130.8, 128.5, 128.4, 128.3, 128.2, 127.9, 127.8, 127.7, 119.3, 103.5, 91.3, 84.8, 81.7, 81.4, 80.2, 78.6, 77.7, 75.7, 75.1, 75.0, 74.8, 73.4, 73.3, 72.5, 68.8.

HRMS (ESI/Q-TOF): m/z [M + NH₄]⁺ calcd for C₇₀H₆₈O₁₂: 1118.5055; found: 1118.5062.

Methyl-O-(2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl)-(1-6)-O-(2,3,4-tri-O-benzyl-α/β-d-glucopyranosyl)-(1-6)-2,3,4-tri-O-benzyl-α/β-d-glucopyranoside (21)

Product 21 was isolated from the reaction between 20 (32 mg, 0.03 mmol, 1 equiv) and B (32 mg, 0.04 mmol, 1.2 equiv) by following GP-2.

Yield: 22 mg (53%, α/β 1.2:1); sticky liquid; R_f = 0.5 (EtOAc/hexane 1:4).

¹H NMR (500 MHz, CDCl₃): δ = 7.72–7.67 (m, 3 H), 7.56–7.50 (m, 4 H), 7.49–7.44 (m, 2 H), 7.37–7.28 (m, 76 H), 7.25–7.22 (m, 8 H), 7.16 (dd, J = 7.4, 2.0 Hz, 2 H), 4.97 (dd, J = 10.8, 7.6 Hz, 2 H), 4.88–4.77 (m, 6 H), 4.66–4.52 (m, 23 H), 4.42 (q, J = 12.1 Hz, 8 H), 3.96 (dd, J = 9.3, 2.8 Hz, 2 H), 3.91 (d, J = 1.0 Hz, 3 H), 3.72–3.57 (m, 9 H), 3.55–3.41 (m, 4 H), 3.38 (s, 2.4 H), 3.36–3.32 (m, 7 H), 3.31 (s, 3 H).

¹³C NMR (125 MHz, CDCl₃): δ = 138.8, 138.7, 138.6, 138.3, 138.1, 137.9, 128.4, 128.4, 128.3, 128.2, 128.12, 127.9, 127.7, 127.4, 104.6, 104.1, 97.8, 97.6, 82.2, 82.0, 81.9, 80.0, 79.9, 79.7, 79.1, 78.1, 78.0, 77.8, 75.6, 75.7, 75.1, 74.9, 74.8, 74.71, 74.4, 73.4, 73.3, 73.2, 72.8, 72.7, 72.5, 70.1, 69.8, 69.3, 68.8, 68.5, 68.4, 66.3, 55.1, 55.0.

Conflict of Interest

The authors declare no conflict of interest.

Acknowledgment

The authors acknowledge SAIF-IIT Patna for providing the HRMS facilities.

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Corresponding Author

Publication History

Received: 26 July 2023

Accepted after revision: 17 October 2023

Accepted Manuscript online:
17 October 2023

Article published online:
20 November 2023

© 2023. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

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• Supplementary Material