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DOI: 10.1055/s-0040-1707312
Synthesis of Fused Pyrimido[1,6-a]indolones via Rhodium(III)-Catalyzed Cascade Annulations
C.R.R. thanks the Science and Engineering Research Board (SERB), New Delhi, for funding the project (EMR/2016/006253). Y.L.P. thanks Department of Science and Technology (DST) for a financial grant under Women Scientists Scheme-A [WOS-A, Grant No. SR/WOS-A/CS-1034/2014 (G)]. S.B. and K.M. thank the Council of Scientific and Industrial Research (CSIR), New Delhi, for research fellowships.
This work is dedicated to Dr. J. S. Yadav on the occasion of his 70th birthday for his contributions to organic synthesis
Abstract
A novel method for the synthesis of fused pyrimido[1,6-a]-indolone derivatives by annulation of 2-alkynylaryl aldehydes/2-alkynylarylidene ketones with N-(pivaloyloxy)-1H-indole-1-carboxamide catalyzed by rhodium has been accomplished. The reaction proceeds through C–H activation based annulation with alkyne moiety followed by addition of nitrogen on to aldehyde/activated alkene to give the products in moderate to good yields. Highly fluorescent dipyrrinone analogues could be synthesized from the derived products.
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Key words
N-(pivaloyloxy)-1H-indole-1-carboxamide - C–H activation - aza-Michael addition - cascade annulation - pyrimido[1,6-a]indoloneIndole-based polycyclic structures are of immense importance due to their widespread presence in various alkaloids and have attracted significant attention in both organic and medicinal chemistry.[1] [2] In particular, the pyrimido[1,6-a]indolone is found in various biologically active natural products and in pharmaceuticals, acting as 5-HT3 receptor antagonist, topoisomerase II inhibitors, etc. (Figure [1]).[3] Due to their promising fluorescent properties they are also widely applied in material chemistry. A series of new analogues of this motif have been prepared and studied for their photophysical properties.[4] In view of the importance of these scaffolds, there have been significant efforts in developing rapid and efficient methods towards the construction of pyrimido[1,6-a]indolones.[5] [6] Among them, [4+2] annulation of indole-1-carboxamides with various two-carbon coupling partners such as alkynes,[5a] alkenes,[5a] [b] α-halo ketones,[5c] diazo compounds[5d] was found to be an attractive strategy. However, despite significant advancement, all these reactions are usually limited to the mono-annulation through the insertion of two carbon agent. To the best of our knowledge, there is only one literature report available for the cascade annulation of indole-1-carboxamides with 1,6-enynes to polycyclic-indole motif.[7] Hence, the development of cascade annulations of indole-1-carboxamides still remains inspiring to explore towards the synthesis of polycyclic fused pyrimido[1,6-a]indolones.
On the other hand, [RhIIICp*]-catalyzed C–H activation and oxidative annulation reactions is an emerging strategy to access diverse heterocyclic compounds.[8] Since, the discovery of N-pivaloyloxy group as an internal oxidant that plays dual role as both directing and oxidizing group by Fagnou and co-workers,[9] it was extensively used to construct a wide variety of nitrogen containing heterocycles.[10] Inspired by these findings, we reported a cascade annulation of N-(pivaloyloxy)benzamides with 2-alkynyl aldehydes catalyzed by rhodium.[11a] The reaction proceeds via alkyne insertion followed by addition of N–H on to aldehyde furnishing the products with aminal functionality. The synthetic utility of the reaction was successfully demonstrated by the synthesis of Rosettacin. In 2014, Cui research group reported the N-carboxamides as directing groups for C-2 functionalization of indoles.[5a] Recently, we have studied the reaction of N-(pivaloyloxy)benzamides with 1,5-enynes via C–H activation to access functionalized aromathecins involving Rh(III)-catalyzed domino [4+2] annulation/aza-Michael Addition.[11b] These results prompted us to explore the reactivity of N-(pivaloyloxy)-1H-indole-1-carboxamides with 2-alkynyl aldehydes/activated alkenes. In continuation of our interest towards construction of fused-indole derivatives,[12] herein we report a cascade annulation approach for the synthesis of polycyclic-fused pyrimido[1,6-a]indolones (Scheme [1]).
Initially, the reaction of N-(pivaloyloxy)-1H-indole-1-carboxamide (1) with 2-(pent-1-yn-1-yl)benzaldehyde (2a) subjected to the reaction conditions used in our earlier work: 5 mol% [RhCp*Cl2]2 and CsOAc in acetone at room temperature. To our delight, the reaction progressed smoothly to afford the product 3a in 79% yield (Table [1], entry 1). The reactions in other solvents like MeCN, t-AmOH, DMF, and MeOH proved that acetone is the best choice of solvent (entries 2–5). The reaction in the presence of Pd(OAc)2 found to be futile (entry 6). Use of various bases such as NaOAc, Cs2CO3, and K2CO3 resulted in the formation of product 3a in low yields (entries 7 to 9).
a Reaction conditions: 1 (1.0 equiv), alkynyl aldehyde 2a (1.2 equiv), catalyst (5 mol%), and base (2 equiv) in solvent (2 mL).
b Isolated yield.
We next investigated the scope of the reaction (Table [2]). The reactions of alkynyl aldehydes with varying alkyl chains on alkyne 2b (R1 = C4H9) and 2c (R1 = C5H11) afforded the desired products 3b and 3c in 73 and 72% yield, respectively (Table [2], entries 2, 3). In the same way, the alkynes bearing substituents like hydroxymethyl (2d) gave the corresponding product 3d in 78% yield (entry 4). In all reactions, the regioselective insertion of internal alkyne was observed to provide pyrimido-indolones. Notably, the reaction of N-(pivaloyloxy)-1H-indole-1-carboxamide with terminal alkynyl enone, 2-ethynylbenzaldehyde (2e), ensued well to afford the product 3e in 72% yield (entry 5) under the present reaction conditions. The alkynyl aldehyde 2f bearing nitro group on the phenyl ring was also participated in the cascade annulations to give 3f in 76% yield (entry 6). Pleasingly, the replacement of a phenyl ring of alkynyl aldehyde with heteroaromatic rings like pyridine- and quinoline-based alkynyl aldehydes underwent the annulations smoothly under the reaction conditions to give the corresponding products 3g and 3h in 70 and 78%, respectively (entries 7, 8).
a Reaction conditions: 1 (1.0 equiv), alkynyl aldehyde 2 (1.2 equiv), [RhCp*Cl2]2 (5 mol%), and CsOAc (2 equiv) in acetone (2 mL).
b Isolated yield.
a Reaction conditions: 1 (1.0 equiv), alkynylbenzylidene ketone 4 (1.2 equiv), [RhCp*Cl2]2 (5 mol%), and CsOAc (2 equiv) in acetone (2 mL).
b Isolated yield.
With these successful results in hand, we envisioned to expand the method to o-alkynylbenzylidene ketones, wherein alkyne insertion with subsequent aza-Michael addition of nitrogen on to α,β-unsaturated carbonyl moiety would lead to the annulated products (Table [3]). We initiated our studies with the reaction of (Z)-4-[2-(pent-1-yn-1-yl)phenyl]but-3-en-2-one (4a) with N-(pivaloyloxy)-1H-indole-1-carboxamide (1) under the above optimized conditions. Gratifyingly, the reaction produced the desired product 5a in 81% yield (Table [3], entry 1). Next, the scope of the reaction with variable substituents on alkyne such as n-butyl (4b), n-pentyl (4c), CH2OH (4d), and cyclopropyl (4e) were studied. All the substrates were well tolerated in the annulation with 1 to furnish the corresponding fused pyrimido[1,6-a]indolones 5b–e in good yields (entries 2–5). The (Z)-4-(2-ethynylphenyl)but-3-en-2-one (4f) having terminal alkyne successfully delivered 5f in 78% yield (entry 6). The 1,5-enynones bearing electronically different groups on the phenyl ring like nitro (5g), methylenedioxy (5h) were compatible in the present cascade annulations to offer the products 5g to 5h in good yields (entries 7, 8). The reaction of N-(pivaloyloxy)-1H-indole-1-carboxamide with heterocyclic based enynones, pyridyl-enynone 4i and quinolinyl-enynone 4j, furnished the corresponding annulated proucts 5i and 5j in 78 and 64% yield, respectively (entries 9, 10).
Further, to expand the scope of the electron-withdrawing group, a few alkynyl substrates were examined (Table [4]). Delightfully, the reaction of 1a with (E)-3-(2-ethynylphenyl)acrylonitrile (4k) provided the fused pyrimido[1,6-a]indolone 5k in 80% yield (Table [4], entry 1). Likewise, the substrate having conjugated ester group (CO2Me, 4l) is also found to be suitable for the present cascade-annulation to offer the corresponding product 5l in 55% yield (entry 2). However, the reaction (E)-1-ethynyl-2-[2-(methylsulfinyl)vinyl]benzene (4m) with 1 with 5m failed to provide the desired product, instead alkyne insertion product 6 was isolated in 73% yield (entry 3).
a Reaction conditions: 1 (1.0 equiv), alkynylbenzylidene ketone 4 (1.2 equiv), [RhCp*Cl2]2 (5 mol%), and CsOAc (2 equiv) in acetone (2 mL).
b Isolated yield.
Based on the above outcomes, a feasible mechanism is proposed as shown in Scheme [2]. The reaction involves insertion of alkyne into the five-membered rhodacycle B via C–H activation based C–C bond formation. Subsequent reductive elimination and oxidative addition of N–O bond (C and D) leads to pyrimido[1,6-a]indolone E. Next, base-promoted addition of amide NH on to aldehyde takes place, similar to the reported cascade reactions.[10c] [f] In the case of alkynyl enones (Tables 2 and 3), aza-Michael addition of NH to the conjugated olefin provides the desired product 5.
To demonstrate the additional transformations of the obtained products, fused pyrimido[1,6-a]indolone 3b was synthesized in gram scale and subjected to further oxidation in the presence of Dess–Martin periodinane (DMP), which led to the formation of pyrimido[1,6-a]indole-6,8-dione 7 in 50% yield (Scheme [3]). This compound holds bridging of the two nitrogens with a carbonyl group, which might results in a dramatic increase in fluorescence like in dipyrrinones.[13] Therefore, the developed method paves the way for expeditious synthesis of N,N′-carbonyl derivatives.
In conclusion, an efficient method has been developed for the construction of fused pyrimido[1,6-a]indolones from the annulation of N-(pivaloyloxy)-1H-indole-1-carboxamide with 1,5-enynones. The reaction involves cascade Rh(III)-catalyzed C–H activation, alkyne insertion and addition of amide nitrogen to aldehyde to provide the products with aminal functionality, which can be further oxidized. The reaction was also found to be effective with substrates bearing activated alkenes, wherein alkyne insertion/aza-Michael addition sequence provides the annulated products in good yields.
All the reactions were performed in oven-dried glass apparatus. Air and moisture sensitive reactions were carried out under inert atmosphere (N2) using freshly distilled anhydrous solvents. Commercially available reagents were used as received without any purification. All reactions were monitored by TLC carried out on silica plates using UV light and anisaldehyde for visualization. Column chromatography was performed on silica gel (100–200 mesh) using hexanes and EtOAc as eluent. 1H NMR was recorded in CDCl3 and DMSO-d 6 on 500 MHz, 400 MHz and 300 MHz. 13C NMR was recorded on 125 MHz, 100 MHz and 75 MHz, using TMS as an internal standard. Chemical shifts are given in ppm and J values are given in hertz (Hz). δ = 7.26 and 77 are the residual peaks of CDCl3 in 1H NMR and 13C NMR, respectively; δ = 2.50 and 39.52 are the residual peaks of DMSO-d 6 in 1H NMR and 13C NMR, respectively. FTIR spectra were recorded on alpha (Bruker) IR spectrophotometer. High-resolution mass spectra (HRMS) [ESI+] were obtained using either a TOF or a double focusing spectrometer.
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Starting Materials
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N-(Pivaloyloxy)-1H-indole-1-carboxamide (1)[5a]
N-(Pivaloyloxy)-1H-indole-1-carboxamide (1) was prepared using the literature procedure, and the data were compared with the reported data.
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2-Alkynyl Aldehydes 2a–h; General Procedure
To a solution of 2-bromoaryl aldehyde (1.0 equiv) and 1-alkyne (1.2 equiv) in NEt3 was added PdCl2(PPh3)2 (2 mol%). The mixture was stirred for 5 min and CuI (1 mol%) was added. The resulting mixture was then heated under N2 atmosphere at 50 °C until completion of the reaction. After cooling, the solution was filtered, and the solid was washed several times with Et2O. After evaporation of the solvent, the product was purified by column chromatography on silica gel (eluent: 5% EtOAc in hexanes) to afford compound 2.
2-Alkynyl aldehydes 2a,[14a] 2b,[14b] 2c,[14c] 2d,[14d] 2e,[14b] 2g,[14e] 2h [14e] are known compounds. They were characterized by spectral data, which were in agreement with literature values.
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5-Nitro-2-(pent-1-yn-1-yl)benzaldehyde (2f)
To a solution of 2-bromo-5-nitrobenzaldehyde (200 mg, 0.87 mmol) and 1-pentyne (71 mg, 1.04 mmol) in NEt3 (5 mL) was added PdCl2(PPh3)2 (12.2 mg, 0.0174 mmol, 2 mol%). The mixture was stirred for 5 min and CuI (1.7 mg, 0.0087 mmol, 1 mol%) was added. The resulting mixture was then heated under N2 atmosphere at 50 °C for 4 h. After cooling, the solution was filtered, and the solid was washed several times with Et2O. After evaporation of the solvent, the product was purified by column chromatography on silica gel (eluent: 5% EtOAc in hexanes) to afford the compound 2f as a yellow oil; yield: 152 mg (80%).
IR (KBr): 3094, 2965, 2228, 1704, 1528, 1350, 749 cm–1.
1H NMR (400 MHz, CDCl3): δ = 10.54 (s, 1 H), 8.71 (d, J = 2.4 Hz, 1 H), 8.35 (dd, J = 8.5, 2.4 Hz, 1 H), 7.68 (d, J = 8.5 Hz, 1 H), 2.54 (t, J = 7.0 Hz, 2 H), 1.78–1.63 (m, 2 H), 1.09 (t, J = 7.4 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 189.8, 146.9, 136.7, 134.6, 133.5, 127.6, 122.3, 104.3, 75.7, 21.8, 21.8, 13.7.
HRMS-ESI: m/z calcd for C12H12NO3 [M + H]+: 218.0817; found: 218.0823.
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Rh(III)-Catalyzed Cascade Annulation; General Procedure
To a solution of N-(pivaloyloxy)-1H-indole-1-carboxamide 1 (0.38 mmol, 1 equiv) and 2-alkynyl aldehyde 2 or alkynyl enone 4 (0.46 mmol, 1.2 equiv) in anhyd acetone (2.0 mL) were added [RhCp*Cl2]2 (0.019 mmol, 0.05 equiv) and CsOAc (0.76 mmol, 2 equiv) under N2 atmosphere and the reaction mixture was stirred for the given time (Tables 1 and 2) at rt. After completion of the reaction (monitored by TLC), the mixture was filtered through Celite and washed with CH2Cl2 (3 × 10 mL). The combined filtrates were concentrated under reduced pressure and the resultant residue was purified by column chromatography over silica gel (eluent: 7% EtOAc in hexanes) to obtain the corresponding pyrimido[1,6-a]indolone 3 or 5.
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8-Hydroxy-13-propylisoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-(8H)-one (3a)
White solid; yield: 100 mg (79%); mp 185–187 °C.
IR (KBr): 3690, 3311, 2937, 1678, 1463, 1397, 1062, 756 cm–1.
1H NMR (500 MHz, DMSO-d 6): δ = 8.60–8.53 (m, 1 H), 7.89 (d, J = 7.8 Hz, 1 H), 7.74–7.68 (m, 1 H), 7.66–7.58 (m, 2 H), 7.54 (t, J = 7.4 Hz, 1 H), 7.37–7.31 (m, 2 H), 7.29 (d, J = 7.8 Hz, 1 H), 6.92 (s, 1 H), 6.77 (d, J = 7.7 Hz, 1 H), 3.06–2.94 (m, 2 H), 1.73 (dt, J = 14.9, 7.5 Hz, 2 H), 1.09 (t, J = 7.3 Hz, 3 H).
13C NMR (100 MHz, DMSO-d 6): δ = 146.1, 141.0, 138.1, 132.9, 132.9, 131.3, 130.4, 130.2, 129.6, 124.8, 123.6, 123.3, 122.6, 120.0, 115.2, 107.6, 98.2, 82.7, 27.7, 22.0, 13.9.
HRMS (ESI): m/z calcd for C21H19N2O2 [M + H]+: 331.1447; found: 331.1456.
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13-Butyl-8-hydroxyisoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-6(8H)-one (3b)
Yellow solid; yield: 96 mg (73%); mp 190–192 °C.
IR (KBr): 3633, 3319, 2955, 2860, 1669, 1394, 1044, 752 cm–1.
1H NMR (500 MHz, DMSO-d 6): δ = 8.55 (dd, J = 6.0, 2.8 Hz, 1 H), 7.85 (d, J = 7.8 Hz, 1 H), 7.70 (dd, J = 5.7, 2.9 Hz, 1 H), 7.60 (dd, J = 17.6, 7.5 Hz, 2 H), 7.52 (t, J = 7.4 Hz, 1 H), 7.37–7.26 (m, 3 H), 6.87 (s, 1 H), 6.75 (d, J = 7.7 Hz, 1 H), 3.06–2.92 (m, 2 H), 1.74–1.61 (m, 2 H), 1.58–1.47 (m, 2 H), 0.95 (t, J = 7.3 Hz, 3 H).
13C NMR (100 MHz, DMSO-d 6): δ = 146.1, 140.9, 137.9, 132.9, 132.7, 131.3, 130.4, 130.1, 129.5, 124.8, 123.5, 123.2, 122.5, 119.9, 115.1, 107.7, 98.0, 82.6, 30.9, 25.7, 22.2, 13.9.
HRMS (ESI): m/z calcd for C22H21N2O2 [M + H]+: 345.1603; found: 345.1614.
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8-Hydroxy-13-pentylisoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-(8H)-one (3c)
Yellow solid; yield: 97 mg (72%); mp 193–194 °C.
IR (KBr): 3751, 3621, 3380, 2924, 1698, 1465, 1380, 755 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.67–8.59 (dd, J = 6.0, 3.3 Hz, 1 H), 7.78 (d, J = 7.7 Hz, 1 H), 7.68 (dd, J = 11.2, 5.3 Hz, 2 H), 7.56 (t, J = 7.2 Hz, 1 H), 7.49 (t, J = 7.2 Hz, 1 H), 7.41–7.33 (m, 2 H), 6.94 (d, J = 3.3 Hz, 1 H), 6.71 (s, 1 H), 4.71 (s, 1 H), 3.07–2.87 (m, 2 H), 1.83–1.74 (m, J = 15.7, 7.9 Hz, 2 H), 1.56–1.49 (m, 2 H), 1.48–1.38 (m, J = 14.3, 7.1 Hz, 2 H), 0.94 (t, J = 7.2 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 147.9, 138.7, 138.3, 133.6, 132.7, 132.4, 130.8, 130.6, 129.6, 125.3, 124.1, 123.4, 123.3, 120.0, 115.9, 109.5, 98.9, 83.4, 32.3, 28.7, 26.9, 22.8, 14.2.
HRMS (ESI): m/z calcd for C23H23N2O2 [M + H]+: 359.1760; found: 359.1752.
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8-Hydroxy-13-(hydroxymethyl)isoindolo[2′,1′:3,4]pyrimido-[1,6-a]indol-6(8H)-one (3d)
Brown solid; yield: 95 mg (78%); mp 215–217 °C.
IR (KBr): 3755, 3631, 3311, 2926, 1686, 1546, 1047, 760 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.59–8.53 (m, 1 H), 8.05 (d, J = 7.5 Hz, 1 H), 7.72 (dd, J = 5.8, 2.7 Hz, 1 H), 7.65–7.53 (m, 3 H), 7.40–7.31 (m, 3 H), 6.95 (s, 1 H), 6.79 (d, J = 7.6 Hz, 1 H), 5.40 (t, J = 5.2 Hz, 1 H), 4.89 (d, J = 5.2 Hz, 2 H).
13C NMR (125 MHz, DMSO-d 6): δ = 146.1, 141.1, 137.5, 135.3, 132.8, 130.9, 130.4, 129.9, 129.8, 124.5 (2 C), 123.6, 122.4, 119.9, 115.1, 106.9, 97.9, 82.9, 55.1.
HRMS (ESI): m/z calcd for C19H15N2O3 [M + H]+: 319.1083; found: 319.1095.
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8-Hydroxyisoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-6(8H)-one (3e)
White solid; yield: 80 mg (72%); mp 205–207 °C.
IR (KBr): 3570, 3625, 2926, 2453, 1693, 1549, 748 cm–1.
1H NMR (400 MHz, DMSO-d 6): δ = 8.59–8.52 (m, 1 H), 7.98–7.92 (m, 1 H), 7.72–7.65 (m, 1 H), 7.65–7.60 (m, 1 H), 7.59–7.51 (m, 2 H), 7.39 (d, J = 8.1 Hz, 1 H), 7.37–7.30 (m, 2 H), 7.26 (s, 1 H), 6.82 (d, J = 8.0 Hz, 1 H), 6.74 (s, 1 H).
13C NMR (100 MHz, DMSO-d 6): δ = 146.4, 140.5, 137.8, 136.3, 132.6, 131.1, 130.6, 130.3, 129.9, 124.6, 123.6, 122.4, 121.3, 119.8, 115.1, 98.6, 91.2, 83.6.
HRMS (ESI): m/z calcd for C18H13N2O2 [M + H]+: 289.0977; found: 289.0984.
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8-Hydroxy-10-nitro-13-propylisoindolo[2′,1′:3,4]pyrimido-[1,6-a]indol-6(8H)-one (3f)
Red solid; yield: 109 mg (76%); mp 200–202 °C.
IR (KBr): 3406, 2255, 2130, 1656, 997, 762 cm–1.
1H NMR (400 MHz, DMSO-d 6): δ = 8.57–8.47 (m, 1 H), 8.38–8.28 (m, 2 H), 8.04 (d, J = 8.6 Hz, 1 H), 7.75–7.67 (m, 1 H), 7.57 (d, J = 7.6 Hz, 1 H), 7.39–7.29 (m, 2 H), 7.05 (s, 1 H), 6.83 (d, J = 7.5 Hz, 1 H), 3.10–2.92 (m, 2 H), 1.78–1.65 (m, 2 H), 1.09 (t, J = 7.2 Hz, 3 H).
13C NMR (75 MHz, CDCl3 + DMSO-d 6): δ = 147.1, 145.6, 141.8, 137.1, 136.9, 133.0, 130.7, 129.9, 125.1, 123.7, 123.4, 122.9, 119.9, 119.8, 115.1, 111.3, 99.8, 81.9, 27.8, 21.9, 13.8.
HRMS (ESI): m/z calcd for C21H16N3O4 [M – H]+: 374.1141; found: 374.1145.
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5-Hydroxy-14-propylpyrido[2′′,3′′:3′,4′]pyrrolo[1′,2′:3,4]-pyrimido[1,6-a]indol-7(5H)-one (3g)
Yellow solid; yield: 89 mg (70%); mp 173–175 °C.
IR (KBr): 3746, 3594, 2959, 1692, 1400, 786 cm–1.
1H NMR (400 MHz, DMSO-d 6): δ = 8.77 (dd, J = 4.8, 1.4 Hz, 1 H), 8.63–8.53 (m, 1 H), 8.04 (dd, J = 7.7, 1.0 Hz, 1 H), 7.78–7.68 (m, 1 H), 7.49 (dd, J = 7.7, 4.9 Hz, 1 H), 7.46 (d, J = 8.0 Hz, 1 H), 7.39–7.34 (m, 2 H), 6.98 (s, 1 H), 6.82 (d, J = 8.0 Hz, 1 H), 3.46–3.27 (m, 2 H), 1.82–1.70 (m, 2 H), 1.02 (t, J = 7.2 Hz, 3 H).
13C NMR (100 MHz, DMSO-d 6): δ = 151.9, 146.6, 138.0, 135.7, 133.4, 133.3, 132.3, 131.6, 130.8, 124.2, 124.1, 123.4, 120.7, 115.7, 110.1, 99.8, 81.8, 26.8, 22.9, 14.3.
HRMS (ESI): m/z calcd for C20H18N3O2 [M + H]+: 332.1399; found: 332.1388.
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8-Hydroxy-15-propylindolo[1′′,2′′:3′,4′]pyrimido[1′,6′:1,2]-pyrrolo[3,4-b]quinolin-6(8H)-one (3h)
Green solid; yield: 114 mg (78%); mp 198–200 °C.
IR (KBr): 3748, 3608, 2923, 2321, 1669, 747 cm–1.
1H NMR (400 MHz, DMSO-d 6): δ = 8.57–8.53 (m, 1 H), 8.52 (s, 1 H), 8.03 (t, J = 7.7 Hz, 2 H), 7.77 (t, J = 7.7 Hz, 1 H), 7.69 (dd, J = 6.3, 2.6 Hz, 1 H), 7.59 (t, J = 7.5 Hz, 1 H), 7.46 (d, J = 8.2 Hz, 1 H), 7.34–7.28 (m, 2 H), 6.98 (s, 1 H), 6.87 (d, J = 8.1 Hz, 1 H), 3.54–3.38 (m, 2 H), 1.81–1.70 (m, 2 H), 1.04 (t, J = 7.4 Hz, 3 H).
13C NMR (100 MHz, DMSO-d 6): δ = 152.6, 148.8, 146.1, 137.4, 133.1, 132.9, 132.8, 132.3, 132.2, 130.6, 130.3, 129.2, 128.7, 127.2, 123.7, 123.1, 120.3, 115.3, 111.2, 99.8, 80.9, 26.7, 22.6, 14.0.
HRMS (ESI): m/z calcd for C24H20N3O2 [M + H]+: 382.1556; found: 382.1550.
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2-Alkynyl Enones 4a–h; General Procedure
A solution of the respective aldehyde (1 equiv) and 1-(triphenylphosphoranylidene)propan-2-one (1.2 equiv) in toluene (0.5 M) was stirred at 90 °C for 4 h. After completion of the reaction (confirmed by TLC), the reaction mixture was allowed to attain rt and concentrated under reduced pressure. The obtained crude product was purified by column chromatography over silica gel using hexane/EtOAc as eluent.
2-Alkynyl enones 4a,[15a] 4b,[15b] 4f,[15c] 4i,[15d] 4k,[15e] and 4l [15f] are known compounds. They were characterized by spectral data, which were in agreement with literature values.
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(E)-4-[2-(Hept-1-yn-1-yl)phenyl]but-3-en-2-one (4c)
Following the general procedure, a solution of 2-(hept-1-yn-1-yl)benzaldehyde (200 mg, 1.0 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (381 mg, 1.2 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. The obtained crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4c as a brown oil; yield: 228 mg (95%).
IR (KBr): 2937, 2228, 1674, 1470, 1256, 983, 761 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.05 (d, J = 16.5 Hz, 1 H), 7.65–7.59 (m, 1 H), 7.49–7.42 (m, 1 H), 7.33–7.27 (m, 2 H), 6.71 (d, J = 16.5 Hz, 1 H), 2.50 (t, J = 7.1 Hz, 2 H), 2.41 (s, 3 H), 1.70–1.62 (m, 2 H), 1.52–1.44 (m, 2 H), 1.42–1.31 (m, 2 H), 0.95–0.89 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 198.84, 142.03, 135.60, 132.95, 129.95, 128.45, 127.94, 125.90, 125.29, 97.28, 78.29, 31.21, 28.47, 26.94, 22.29, 19.66, 14.03.
HRMS-ESI: m/z calcd for C17H21O [M + H]+: 241.1592; found: 241.1577.
#
(E)-4-[2-(3-Hydroxyprop-1-yn-1-yl)phenyl]but-3-en-2-one (4d)
Following the general procedure, a solution of 2-(3-hydroxyprop-1-yn-1-yl)benzaldehyde (200 mg, 1.25 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (477 mg,1.5 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. After completion of the reaction (confirmed by TLC), the reaction mixture was allowed to attain rt and concentrated under reduced pressure. The obtained crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4d as a brown oil; yield: 240 g (96%).
IR (KBr): 3929, 3644, 3411, 2924, 1668, 1363, 1261, 1031, 762 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.01 (d, J = 16.4 Hz, 1 H), 7.63–7.58 (m, 1 H), 7.49–7.44 (m, 1 H), 7.35–7.28 (m, 2 H), 6.75 (d, J = 16.4 Hz, 1 H), 4.57 (s, 2 H), 2.40 (s, 3 H).
13C NMR (100 MHz, CDCl3): δ = 199.1, 141.4, 135.7, 133.1, 130.0, 128.8, 128.3, 126.1, 123.9, 93.9, 82.9, 51.5, 27.7.
HRMS-ESI: m/z calcd for C13H12O2Na [M + Na]+: 223.0735; found: 223.0721.
#
(E)-4-[2-(Cyclopropylethynyl)phenyl]but-3-en-2-one (4e)
Following general procedure, a solution of 2-(cyclopropylethynyl)benzaldehyde (200 mg, 1.17 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (381 mg,1.2 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. After completion of the reaction (confirmed by TLC), the reaction mixture was allowed to attain rt and concentrated under reduced pressure. The obtained crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4e (220 mg, 92%) as a pale yellow oil.
IR (KBr): 3843, 3644, 3447, 3046, 2747, 1727, 1255, 760, 647 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.00 (d, J = 16.5 Hz, 1 H), 7.59 (dd, J = 5.1, 4.2 Hz, 1 H), 7.46–7.40 (m, 1 H), 7.32–7.24 (m, 2 H), 6.71 (d, J = 16.5 Hz, 1 H), 2.41 (s, 3 H), 1.58–1.49 (m, 1 H), 0.95 (ddd, J = 8.1, 5.5, 3.4 Hz, 2 H), 0.86 (ddd, J = 7.6, 5.5, 3.5 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 198.87, 142.06, 135.83, 133.03, 130.02, 128.46, 127.97, 126.09, 125.23, 100.49, 73.50, 27.15, 9.12 (2 C), 0.53.
HRMS-ESI: m/z calcd for C15H15O [M + H]+: 211.1123; found: 211.1110.
#
(E)-4-[5-Nitro-2-(pent-1-yn-1-yl)phenyl]but-3-en-2-one (4g)
Following the general procedure, a solution of 5-nitro-2-(pent-1-yn-1-yl)benzaldehyde (200 mg, 0.92 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (351.7 mg, 1.20 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. The crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4g (213 mg, 90%) as a white solid; mp 170–172 °C.
IR (KBr): 3839, 3403, 2968, 2226, 1682, 1522, 1350, 1082, 984 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.47 (d, J = 2.3 Hz, 1 H), 8.14 (dd, J = 8.6, 2.3 Hz, 1 H), 8.00 (d, J = 16.4 Hz, 1 H), 7.60 (d, J = 8.6 Hz, 1 H), 6.86 (d, J = 16.3 Hz, 1 H), 2.54 (t, J = 7.0 Hz, 2 H), 2.43 (s, 3 H), 1.76–1.68 (m, 2 H), 1.11 (t, J = 7.4 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 197.8, 146.9, 139.1, 137.2, 133.9, 131.4, 130.2, 124.1, 121.0, 103.1, 77.7, 28.0, 22.0, 21.9, 13.7.
HRMS-ESI: m/z calcd for C15H16NO3 [M + H]+: 258.1130; found: 258.1118.
#
(E)-4-[2-(Pent-1-yn-1-yl)pyridin-3-yl]but-3-en-2-one (4h)
A solution of 2-(pent-1-yn-1-yl)nicotinaldehyde (200 mg, 1.15 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (441 mg,1.38 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. After completion of the reaction (confirmed by TLC), the reaction mixture was allowed to attain rt and concentrated under reduced pressure. The obtained crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4h as a pale-yellow oil, yield: 236 mg (96%).
IR (KBr): 3850, 3457, 2967, 2227, 1678, 1427, 1260, 985, 804 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.55 (dd, J = 4.7, 1.6 Hz, 1 H), 7.99 (d, J = 16.5 Hz, 1 H), 7.90 (dd, J = 8.0, 1.6 Hz, 1 H), 7.31–7.22 (m, 1 H), 6.73 (d, J = 16.5 Hz, 1 H), 2.53 (t, J = 7.0 Hz, 2 H), 2.42 (s, 3 H), 1.80–1.67 (m, 2 H), 1.11 (t, J = 7.4 Hz. 3 H).
13C NMR (100 MHz, CDCl3): δ = 198.1, 151.1, 143.9, 139.6, 133.2, 131.6, 130.0, 122.6, 97.4, 78.5, 27.2, 21.8, 21.6, 13.7.
HRMS-ESI: m/z calcd for C14H16NO [M + H]+: 214.1232; found: 214.1220.
#
(E)-4-[2-(Pent-1-yn-1-yl)quinolin-3-yl]but-3-en-2-one (4j)
A solution of 2-(pent-1-yn-1-yl)quinoline-3-carbaldehyde (400 mg, 1.73 mmol) and 1-(triphenylphosphoranylidene)propan-2-one (855 mg, 2.69 mmol) in toluene (0.5 M) was stirred at 90 °C for 4 h. After completion of the reaction (confirmed by TLC), the reaction mixture was allowed to attain rt and concentrated under reduced pressure. The obtained crude product was purified by column chromatography over silica gel (10% EtOAc in PE) to afford 4j as a brown solid; yield: 424 mg (90%); mp 100–102 °C.
IR (KBr): 3055, 2963, 2230, 1674, 1256, 1177, 980, 761 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.37 (s, 1 H), 8.14 (d, J = 16.4 Hz, 1 H), 8.06 (d, J = 8.5 Hz, 1 H), 7.81 (d, J = 8.2 Hz, 1 H), 7.76–7.71 (m, 1 H), 7.55 (dd, J = 8.0, 7.1 Hz, 1 H), 6.87 (d, J = 16.4 Hz, 1 H), 2.58 (t, J = 7.1 Hz, 2 H), 2.46 (s, 3 H), 1.77 (dd, J = 14.5, 7.3 Hz, 2 H), 1.14 (t, J = 7.4 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 198.0, 148.5, 143.8, 139.8, 133.4, 131.1, 129.9, 129.3, 128.9, 128.1, 127.6, 126.7, 97.0, 79.1, 27.2, 21.9, 21.7, 13.8.
HRMS-ESI: m/z calcd for C18H18NO [M + H]+: 264.1388; found: 264.1382.
#
(E)-1-Ethynyl-2-[2-(methylsulfinyl)vinyl]benzene (4m)
To a stirred solution of (E)-trimethyl({2-[2-(methylsulfinyl)vinyl]phenyl}ethynyl)silane (800 mg, 3.00 mmol) was added K2CO3 (1.20 g, 9.1 mmol) in MeOH at 0 °C and the mixture was stirred for 30 min to complete the reaction at rt. The obtained crude product was purified by column chromatography over silica gel (7% EtOAc in PE) to afford 4m as a pale yellow oil; yield: 464 mg (80%).
IR (KBr): 3292, 2923, 1733, 1592, 1446, 1242, 944, 761, 654 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.48–7.42 (m, 2 H), 7.28 (td, J = 7.4, 3.9 Hz, 1 H), 7.13 (td, J = 7.5, 1.2 Hz, 1 H), 6.94 (d, J = 15.5 Hz, 1 H), 6.79 (d, J = 15.5 Hz, 1 H), 3.32 (s, 1 H), 2.41 (s, 3 H).
13C NMR (100 MHz, CDCl3): δ = 139.11, 133.35, 129.13, 128.47, 126.30, 124.10, 122.15, 119.43, 82.30, 81.80, 14.80.
HRMS-ESI: m/z calcd for C11H11OS [M + H]+: 191.0531; found: 191.0525.
#
8-(2-Oxopropyl)-13-propylisoindolo[2′,1′:3,4]pyrimido[1,6-a]-indol-6(8H)-one (5a)
Yellow solid; yield: 115 mg (81%); mp 180–182 °C.
IR (KBr): 3515, 3379, 2963, 1682, 1381, 1170, 762 cm–1.
1H NMR (300 MHz, CDCl3 + DMSO-d 6): δ = 8.54 (d, J = 7.7 Hz, 1 H), 7.85 (d, J = 7.8 Hz, 1 H), 7.67 (d, J = 7.1 Hz, 1 H), 7.56–7.42 (m, 3 H), 7.36–7.23 (m, 2 H), 6.80 (s, 1 H), 5.82 (dd, J = 6.9, 3.0 Hz, 1 H), 3.65 (dd, J = 17.5, 3.2 Hz, 1 H), 3.13 (dd, J = 17.5, 7.3 Hz, 1 H), 3.05–2.94 (m, 2 H), 2.13 (s, 3 H), 1.84–1.67 (m, 2 H), 1.11 (t, J = 7.3 Hz, 3 H).
13C NMR (75 MHz, CDCl3 + DMSO-d 6): δ = 205.5, 145.9, 142.1, 138.0, 134.4, 132.4, 131.8, 130.2, 129.3, 128.7, 123.3, 123.2, 123.1, 121.9, 119.5, 115.2, 106.8, 96.8, 58.5, 45.8, 30.3, 27.8, 21.7, 13.8.
HRMS-ESI: m/z calcd for C24H23N2O2 [M + H]+: 371.1760; found: 371.1760.
#
13-Butyl-8-(2-oxopropyl)isoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-6(8H)-one (5b)
Yellow solid; yield: 117 mg (79%); mp 190–192 °C.
IR (KBr): 3563, 3334, 2955, 1693, 1382, 761 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.70–8.63 (m, 1 H), 7.79 (d, J = 7.8 Hz, 1 H), 7.70–7.64 (m, 1 H), 7.53 (d, J = 7.6 Hz, 1 H), 7.47 (t, J = 7.3 Hz, 1 H), 7.44–7.37 (m, 1 H), 7.37–7.30 (m, 2 H), 6.68 (s, 1 H), 5.98 (dd, J = 8.2, 2.5 Hz, 1 H), 3.86 (dd, J = 17.7, 3.1 Hz, 1 H), 3.09–2.97 (m, 2 H), 2.91 (dd, J = 17.7, 8.4 Hz, 1 H), 2.22 (s, 3 H), 1.83–1.71 (m, J = 12.2, 7.6 Hz, 2 H), 1.63–1.52 (m, 2 H), 1.03 (t, J = 7.3 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 205.8, 146.9, 142.5, 138.4, 134.2, 133.3, 132.6, 130.7, 129.4, 128.9, 123.8 (2 C), 123.4, 122.6, 119.6, 116.1, 108.3, 97.4, 58.9, 47.2, 31.1, 30.7, 26.7, 23.2, 14.2.
HRMS (ESI): m/z calcd for C25H25N2O2 [M + H]+: 385.1916; found: 385.1917.
#
8-(2-Oxopropyl)-13-pentylisoindolo[2′,1′:3,4]pyrimido[1,6-a]-indol-6(8H)-one (5c)
Yellow solid; yield: 119 mg (78%); mp 178–180 °C.
IR (KBr): 3710, 3523, 3425, 3141, 2925, 1691, 1377, 760 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.69–8.64 (m, 1 H), 7.78 (d, J = 7.8 Hz, 1 H), 7.70–7.64 (m, 1 H), 7.53 (d, J = 7.6 Hz, 1 H), 7.47 (t, J = 7.4 Hz, 1 H), 7.41 (t, J = 7.2 Hz, 1 H), 7.38–7.32 (m, 2 H), 6.68 (s, 1 H), 5.98 (dd, J = 8.3, 3.0 Hz, 1 H), 3.86 (dd, J = 17.7, 3.1 Hz, 1 H), 3.04–2.97 (m, 2 H), 2.91 (dd, J = 17.7, 8.4 Hz, 1 H), 2.22 (s, 3 H), 1.81–1.74 (m, 2 H), 1.59–1.50 (m, 2 H), 1.47–1.40 (m, 2 H), 0.95 (t, J = 7.3 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 205.9, 147.1, 142.6, 138.4, 134.2, 133.3, 132.7, 130.8, 129.9, 129.0, 123.8, 123.8, 123.5, 122.7, 119.7, 116.1, 108.4, 97.4, 58.9, 47.3, 32.3, 30.7, 28.7, 27.0, 22.8, 14.3.
HRMS (ESI): m/z calcd for C26H27N2O2 [M + H]+: 399.2073; found: 399.2057.
#
13-(Hydroxymethyl)-8-(2-oxopropyl)isoindolo[2′,1′:3,4]-pyrimido[1,6-a]indol-6(8H)-one (5d)
Yellow solid; yield: 113 mg (82%); mp 181–183 °C.
IR (KBr): 3513, 3023, 1694, 1387, 758 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.52 (d, J = 7.0 Hz, 1 H), 8.02 (d, J = 7.9 Hz, 1 H), 7.54 (d, J = 7.4 Hz, 1 H), 7.47 (t, J = 6.6 Hz, 1 H), 7.42–7.35 (m, 2 H), 7.26 (d, J = 23.1 Hz, 3 H), 6.71 (s, 1 H), 5.77 (d, J = 7.9 Hz, 1 H), 5.12–4.99 (m, 2 H), 3.75 (d, J = 17.6 Hz, 1 H), 2.85 (dd, J = 17.7, 8.3 Hz, 1 H), 2.18 (s, 3 H), 1.71 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 205.7, 146.8, 142.6, 137.5, 137.1, 133.0, 131.5, 130.6, 130.2, 129.2, 124.6, 123.9, 123.4, 122.8, 119.7, 115.8, 105.7, 97.2, 59.1, 57.3, 46.8, 30.7.
HRMS (ESI): m/z calcd for C22H19N2O3 [M + H]+: 359.1394; found: 359.1396.
#
13-Cyclopropyl-8-(2-oxopropyl)isoindolo[2′,1′:3,4]pyrimido-[1,6-a]indol-6(8H)-one (5e)
Yellow solid; yield: 105 mg (74%); mp 180–182 °C.
IR (KBr): 3893, 3015, 1694, 1467, 1379, 760 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.65 (d, J = 7.8 Hz, 1 H), 8.29 (d, J = 7.8 Hz, 1 H), 7.67 (dd, J = 6.8, 1.4 Hz, 1 H), 7.52 (d, J = 7.6 Hz, 1 H), 7.47 (t, J = 7.3 Hz, 1 H), 7.44–7.39 (m, J = 7.4, 0.9 Hz, 1 H), 7.37–7.30 (m, 2 H), 6.90 (s, 1 H), 5.96 (dd, J = 8.4, 2.9 Hz, 1 H), 3.85 (dd, J = 17.7, 3.1 Hz, 1 H), 2.90 (dd, J = 17.7, 8.4 Hz, 1 H), 2.21 (s, 3 H), 2.07–1.95 (m, 1 H), 1.32–1.19 (m, 2 H), 0.92–0.78 (m, 2 H).
13C NMR (100 MHz, CDCl3): δ = 205.8, 147.0, 142.7, 138.5, 137.6, 133.1, 132.4, 130.8, 129.7, 128.6, 125.2, 123.8, 123.5, 122.6, 119.7, 116.0, 107.7, 98.8, 59.1, 47.2, 30.7, 9.1, 8.0.
HRMS-ESI: m/z calcd for C24H21N2O2 [M]+: 369.1603; found: 369.1603.
#
8-(2-Oxopropyl)isoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-6(8H)-one (5f)
Yellow solid; yield: 98 mg (78%); mp 175–177 °C.
IR (KBr): 3830, 3520, 3025, 1693, 1380, 759 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.68–8.60 (m, 1 H), 7.69–7.60 (m, 2 H), 7.50 (d, J = 6.9 Hz, 1 H), 7.47–7.38 (m, 2 H), 7.37–7.29 (m, 2 H), 6.81 (s, 1 H), 6.58 (s, 1 H), 5.96 (dd, J = 8.5, 2.7 Hz, 1 H), 3.90 (dd, J = 17.8, 3.1 Hz, 1 H), 2.91 (dd, J = 17.8, 8.6 Hz, 1 H), 2.22 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 205.7, 147.4, 142.0, 139.3, 136.3, 133.1, 132.0, 131.1, 130.4, 128.9, 123.9 (2C), 122.6, 120.9, 119.7, 115.9, 98.4, 90.9, 59.6, 46.7, 30.7.
HRMS (ESI): m/z calcd for C21H17N2O2 [M + H]+: 329.1290; found: 329.1280.
#
10-Nitro-8-(2-oxopropyl)-13-propylisoindolo[2′,1′:3,4]pyrimido-[1,6-a]indol-6(8H)-one (5g)
Brown solid; yield: 131 mg (82%); mp 200–202 °C.
IR (KBr): 3797, 3531, 3372, 2923, 1696, 1342, 758 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.67–8.61 (m, 1 H), 8.38–8.30 (m, 2 H), 7.86 (d, J = 8.6 Hz, 1 H), 7.72–7.64 (m, 1 H), 7.41–7.34 (m, 2 H), 6.81 (s, 1 H), 5.98 (dd, J = 8.0, 2.5 Hz, 1 H), 3.86 (dd, J = 18.2, 2.9 Hz, 1 H), 3.10 (dd, J = 18.2, 8.0 Hz, 1 H), 3.05–2.99 (m, 2 H), 2.23 (s, 3 H), 1.88–1.77 (m, 2 H), 1.16 (t, J = 7.4 Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 205.3, 147.9, 146.6, 143.6, 138.7, 137.5, 133.5, 132.5, 130.6, 124.7, 124.2, 123.7, 123.6, 120.2, 119.4, 116.1, 111.9, 99.7, 58.7, 46.5, 30.6, 29.0, 22.4, 14.5.
HRMS (ESI): m/z calcd for C24H22N3O4 [M + H]+: 416.1610; found: 416.1613.
#
5-(2-Oxopropyl)[1,3]dioxolo[4′′,5′′:5′,6′]isoindolo[2′,1′:3,4]-pyrimido[1,6-a]indol-7(5H)-one (5h)
Yellow solid: yield: 110 mg (77%); mp 235–247 °C.
IR (KBr): 3921, 3521, 3341, 2918, 1695, 1475, 1318, 766 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.61 (d, J = 7.3 Hz, 1 H), 7.61 (d, J = 6.9 Hz, 1 H), 7.40–7.28 (m, 2 H), 6.98 (d, J = 26.9 Hz, 2 H), 6.57 (d, J = 31.6 Hz, 2 H), 6.04 (s, 2 H), 5.83 (d, J = 7.2 Hz, 1 H), 3.91 (d, J = 17.7 Hz, 1 H), 2.83 (dd, J = 17.8, 8.8 Hz, 1 H), 2.22 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 205.9, 150.3, 148.9, 147.2, 139.4, 136.8, 136.4, 132.9, 131.2, 125.5, 123.8, 122.4, 119.5, 115.9, 104.5, 102.2, 100.6, 97.8, 89.3, 59.3, 46.8, 30.3.
HRMS (ESI): m/z calcd for C22H17N2O4 [M + H]+: 373.1188; found: 373.1180.
#
5-(2-Oxopropyl)-14-propylpyrido[2′′,3′′:3′,4′]pyrrolo[1′,2′:3,4]pyrimido[1,6-a]indol-7(5H)-one (5i)
Brown solid; yield: 111 mg (78%); mp 195–197 °C.
IR (KBr): 3712, 3524, 2967, 1686, 1406, 754 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.71–8.64 (m, 2 H), 7.85 (d, J = 7.8 Hz, 1 H), 7.71–7.66 (m, 1 H), 7.41–7.34 (m, 2 H), 7.23 (dd, J = 7.8, 4.8 Hz, 1 H), 6.78 (s, 1 H), 5.96 (dd, J = 9.2, 2.7 Hz, ), 4.05 (dd, J = 18.1, 3.0 Hz, 1 H), 3.44–3.35 (m, 2 H), 2.82 (dd, J = 18.1, 9.3 Hz, 1 H), 2.23 (s, 3 H), 1.86–1.76 (m, 2 H), 1.07 (t, J = 7.4 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 205.9, 152.8, 150.6 147.0, 138.0, 136.4, 133.3, 132.1, 131.7, 130.7, 123.9, 123.0, 122.9, 119.9, 116.1, 111.2, 99.0, 57.1, 46.8, 30.6, 27.1, 22.9, 14.2.
HRMS (ESI): m/z calcd for C23H22N3O2 [M + H]+: 372.1712; found: 372.1715.
#
8-(2-Oxopropyl)-15-propylindolo[1′′,2′′:3′,4′]pyrimido-[1′,6′:1,2]pyrrolo[3,4-b]quinolin-6(8H)-one (5j)
Green solid; yield: 58 mg (64%); mp 240–242 °C.
IR (KBr): 3745, 3700, 3083, 2925, 2855, 1732, 1518, 1217, 1027, 773, 734 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.70 (dd, J = 6.1, 3.3 Hz, 1 H), 8.24 (s, 1 H), 8.13 (d, J = 8.4 Hz, 1 H), 7.82 (d, J = 7.9 Hz, 1 H), 7.77–7.68 (m, 2 H), 7.58–7.52 (m, 1 H), 7.41–7.36 (m, 2 H), 6.86 (s, 1 H), 6.09 (dd, J = 9.3, 1.8 Hz, 1 H), 4.10 (dd, J = 18.2, 2.8 Hz, 1 H), 3.57 (dd, J = 8.6, 7.0 Hz, 2 H), 2.92 (dd, J = 18.2, 9.3 Hz, 1 H), 2.25 (s, 3 H), 1.93–1.83 (m, 2 H), 1.16 (t, J = 7.3 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 206.1, 153.4, 149.2, 147.1, 137.9, 133.9, 133.5, 131.6, 130.9, 130.8, 130.1, 129.9, 128.3, 127.4, 127.2, 123.9, 123.2, 120.1, 116.2, 113.0, 99.5, 56.6, 47.5, 30.6, 27.5, 23.0, 14.4.
HRMS-ESI: m/z calcd for C27H24N3O2 [M + H]+: 422.1869; found: 422.1863.
#
2-(6-Oxo-6,8-dihydroisoindolo[2′,1′:3,4]pyrimido[1,6-a]indol-8-yl)acetonitrile (5k)
Yellow solid; yield: 96 mg (80%); mp 243–245 °C.
IR (KBr): 3896, 3522, 3314, 3021, 2687, 2251, 1695, 1385, 757 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.66–8.58 (m, 1 H), 7.73 (dd, J = 5.4, 3.0 Hz, 1 H), 7.65 (dd, J = 5.8, 3.1 Hz, 2 H), 7.54 (pent, J = 7.4 Hz, 2 H), 7.40–7.34 (m, 2 H), 6.86 (s, 1 H), 6.64 (s, 1 H), 5.71 (dd, J = 6.1, 3.7 Hz, 1 H), 3.57–3.42 (m, 2 H).
13C NMR (125 MHz, CDCl3): δ = 147.4, 138.5, 138.4, 135.8, 133.2, 132.5, 131.1, 130.7, 130.1, 124.2, 123.3, 123.2, 121.5, 119.9, 115.9, 115.8, 99.6, 91.9, 59.0, 22.3.
HRMS-ESI: m/z calcd for C20H14N3O [M + H]+: 312.1137; found: 312.1141.
#
Methyl 2-(6-Oxo-6,8-dihydroisoindolo[2′,1′:3,4]pyrimido-[1,6-a]indol-8-yl)acetate (5l)
Pink solid; yield: 72 mg (55%); mp 113–115 °C.
IR (KBr): 3866, 3698, 3068, 1739, 1696, 1464, 1381, 1222, 762 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.69–8.60 (m, 1 H), 7.70–7.59 (m, 2 H), 7.53–7.41 (m, 3 H), 7.38–7.30 (m, 2 H), 6.81 (s, 1 H), 6.59 (s, 1 H), 5.89 (dd, J = 7.7, 3.5 Hz, 1 H), 3.67 (s, 3 H), 3.62 (dd, J = 16.3, 3.7 Hz, 1 H), 3.02 (dd, J = 16.3, 7.9 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 170.73, 147.39, 141.04, 139.22, 136.23, 133.13, 132.27, 131.07, 130.31, 129.15, 123.87, 123.40, 122.66, 121.06, 119.66, 116.03, 98.51, 90.94, 60.12, 52.03, 37.47.
HRMS-ESI: m/z calcd for C21H16N2O3Na [M + Na]+: 367.1059; found: 367.1053.
#
(E)-3-{2-[2-(Methylsulfinyl)vinyl]phenyl}pyrimido[1,6-a]indol-1(2H)-one (6)
Off-white solid; yield: 97 mg (73%); mp 198–200 °C.
IR (KBr): 3843, 3644, 3447, 3046, 2747, 1727, 1255, 760, 647 cm–1.
1H NMR (400 MHz, DMSO-d 6): δ = 11.05 (s, 1 H), 8.54 (dd, J = 8.0, 0.7 Hz, 1 H), 7.73–7.64 (m, 2 H), 7.46–7.39 (m, 2 H), 7.38–7.26 (m, 3 H), 7.13 (d, J = 15.4 Hz, 1 H), 6.65 (s, 1 H), 6.45 (d, J = 1.6 Hz, 1 H), 6.40 (d, J = 15.5 Hz, 1 H), 2.26 (s, 3 H).
13C NMR (100 MHz, DMSO-d 6): δ = 148.5, 137.3, 136.3, 135.8, 132.6, 131.9, 130.9, 130.3, 129.9, 129.1, 126.9, 125.6, 124.0, 122.3, 121.6, 120.1, 115.8, 99.5, 97.7, 14.5.
HRMS-ESI: m/z calcd for C20H17N2O2S [M + H]+: 349.1011; found: 349.1024.
#
13-Butylisoindolo[2′,1′:3,4]pyrimido[1,6-a]indole-6,8-dione (7)
To a stirred solution of compound 3b (50 mg, 0.145 mmol) in anhydrous CH2Cl2 Dess–Martin periodinane (73.9 mg, 0.174 mmol) was added at 0 °C under N2 atmosphere and the reaction mixture stirred at room temperature for 2 h. It was quenched with a 1:1 mixture of saturated solutions of hypo and NaHCO3 (4 mL) and extracted with CH2Cl2 (2 x 10 mL). The combined organic layer was washed with water (10 mL), brine (10 mL), dried over (Na2SO4), concentrated and the residue was purified by column chromatography on silica gel (15% EtOAc in hexanes) to afford the compound 7.
Yellow solid; yield: 25 mg (50%); mp 190–192 °C.
IR (KBr): 3872, 3728, 3516, 3435, 3021, 1777, 1368, 751 cm–1.
1H NMR (500 MHz, CDCl3): δ = 8.64 (dd, J = 8.2, 0.5 Hz, 1 H), 8.02 (d, J = 7.6 Hz, 1 H), 7.82 (d, J = 7.9 Hz, 1 H), 7.77–7.68 (m, 1 H), 7.60 (d, J = 7.8 Hz, 1 H), 7.54–7.49 (m, 1 H), 7.45–7.35 (m, 1 H), 7.35–7.28 (m, 1 H), 6.81 (s, 1 H), 3.02 (t, J = 8 Hz, 2 H), 1.82–1.74 (m, 2 H), 1.60–1.51 (m, 2 H), 1.04 (t, J = 7.5 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 163.9, 143.7, 135.7, 135.5, 134.6, 133.9, 130.4, 129.5, 128.4, 127.6, 125.7, 125.4, 124.6, 123.1, 120.9, 116.5, 115.4, 104.2, 31.2, 27.0, 23.1, 13.9.
HRMS-ESI: m/z calcd for C22H19N2O2 [M + H]+: 343.1449; found: 343.1447.
#
#
Supporting Information
- Supporting information for this article is available online at https://doi-org.accesdistant.sorbonne-universite.fr/10.1055/s-0040-1707312.
Copies of 1H and 13C NMR spectra for all new compounds are provided.
- Supporting Information
-
References
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For reviews, see:
For selected references, see:
For selected references, see:
For selected references, see:
Corresponding Author
Publication History
Received: 07 August 2020
Accepted after revision: 04 September 2020
Article published online:
12 October 2020
© 2020. Thieme. All rights reserved
Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany
-
References
- 1a Ishikura M, Abe T, Choshi T, Hibino S. Nat. Prod. Rep. 2015; 32: 1389
- 1b Zi W, Zuo Z, Ma D. Acc. Chem. Res. 2015; 48: 702
- 1c Singh AK, Raj V, Saha S. Eur. J. Med. Chem. 2017; 142: 244
- 2a Wang Z, Addepalli Y, He Y. Org. Lett. 2018; 20: 644
- 2b Cai J, Wu B, Rong G, Zhang C, Qui L, Xu X. Org. Lett. 2018; 20: 2733
- 2c Xie C-C, Tan R, Liu Y-K. Org. Chem. Front. 2019; 6: 919
- 3a Hammer H, Winterfeldt E. Tetrahedron 1981; 37: 3609
- 3b Kato M, Nishino S, Ito K, Yamakuni H, Takasugi H. Chem. Pharm. Bull. 1994; 42: 2556
- 3c Kamata J, Okada T, Kotake Y, Niijima J, Nakamura K, Uenaka T, Yamaguchi A, Tsukara K, Nagasu T, Koyanagi N, Kitoh K, Yoshimatsu K, Yoshino H, Sugumi H. Chem. Pharm. Bull. 2004; 52: 1071
- 4a Mizuta M, Seio K, Ohkubo A, Miyata K. J. Org. Chem. 2007; 72: 5046
- 4b Mizuta M, Seio K, Ohkubo A, Sekine M. J. Phy. Chem. B 2009; 113: 9562
- 4c Dell’Acqua M, Ronda L, Piano R, Pellegrino S, Clerici F, Rossi E, Mozzarelli A, Gelmi M, Abbiati G. J. Org. Chem. 2015; 80: 10939
- 5a Zhang Y, Zheng J, Cui S. J. Org. Chem. 2014; 79: 6490
- 5b Zhang L.-B, Zhu M.-H, Du W.-B, Ni S.-F, Wen L.-R, Li M. Chem. Commun. 2019; 55: 14383
- 5c Wu Z.-J, Li y.-Q, Huang Z.-Z. Eur. J. Org. Chem. 2016; 5399
- 5d Chen X, Hu X, Bai S, Deng Y, Jiang H, Zeng W. Org. Lett. 2016; 18: 192
- 6a Facoetti D, Abbiati G, d’Avolio L, Ackermann L, Rossi E. Synlett 2009; 2273
- 6b Zheng J, Zhang Y, Cui S. Org. Lett. 2014; 16: 3560
- 6c Tao L, Shi M. Org. Lett. 2019; 21: 129
- 6d Hussain M, Chen M, Yang S, Wang G.-W. Org. Lett. 2019; 21: 8568
- 6e Zhang L.-B, Zhu M.-H, Ni S.-F, Wen L.-R, Li M. ACS Catal. 2019; 9: 1680
- 7 Reddy CR, Yarlagadda S, Sridhar B, Reddy BV. S. Eur. J. Org. Chem. 2017; 5763
- 8a Satoh T, Miura M. Chem. Eur. J. 2010; 16: 11212
- 8b Hyster TK, Rovis T. J. Am. Chem. Soc. 2010; 132: 10565
- 8c Pham MV, Ye B, Cramer N. Angew. Chem. Int. Ed. 2012; 51: 10610
- 8d Chuang S.-C, Gandeepan P, Cheng C.-H. Org. Lett. 2013; 15: 5750
- 8e Collins KD, Lied F, Glorius F. Chem. Commun. 2014; 50: 4459
- 8f Feng C, Feng D, Loh T-P. Chem. Commun. 2014; 50: 9865
- 8g Zhang X, Si W, Bao M, Asao N, Yamamoto Y, Jin T. Org. Lett. 2014; 16: 4830
- 8h Reddy Chidipudi S, Burns DJ, Khan I, Lam HW. Angew. Chem. Int. Ed. 2015; 54: 13975
- 8i Xu Y, Yang X, Zhou X, Kong L, Li X. Org. Lett. 2017; 19: 4307
- 8j Upadhyay NS, Thorat VH, Sato R, Annamalai P, Chuang S.-C, Cheng C.-H. Green Chem. 2017; 19: 3219
- 8k Li Y, Pi R, Ouyang X-H, Song R-J, Li J-H. Org. Lett. 2019; 21: 397
- 9a Guimond N, Gouliaras C, Fagnou K. J. Am. Chem. Soc. 2010; 132: 6908
- 9b Guimond N, Gorelsky SI, Fagnou K. J. Am. Chem. Soc. 2011; 133: 6449
- 10a Wang H, Glorius F. Angew. Chem. Int. Ed. 2012; 51: 7318
- 10b Yu D-G, de Azambuja F, Gennsch T, Daniliuc CG, Glorius F. Angew. Chem. Int. Ed. 2014; 53: 9650
- 10c Fukui Y, Liu P, Liu Q, He Z-T, Wu N-Y, Tian P, Lin G-Q. J. Am. Chem. Soc. 2014; 136: 15607
- 10d Webb NJ, Marsden SP, Raw SA. Org. Lett. 2014; 16: 4718
- 10e Semakul N, Jackson KE, Paton RS, Rovis T. Chem. Sci. 2017; 8: 1015
- 10f Hong SY, Jeong J, Chang S. Angew. Chem. Int. Ed. 2017; 56: 2408
- 11a Reddy CR, Mallesh K. Org. Lett. 2018; 20: 150
- 11b Reddy CR, Mallesh K, Srinivas B, Reddy DR. J. Org. Chem. 2020; 85: 7905
- 12a Reddy C, Kajare RC, Punna N. Chem. Commun. 2020; 56: 3445
- 12b Reddy CR, Sathish P, Valleti RR. ChemistrySelect 2019; 4: 8229
- 13a Brower JO, Lightner DA. J. Org. Chem. 2002; 67: 2713
- 13b Boiadjiev SE, Lightner DA. Tetrahedron: Asymmetry 2004; 15: 3301
- 13c Woydziak ZR, Boiadjiev SE, Norona WS, McDonagh AF, Lightner DA. J. Org. Chem. 2005; 70: 8417
- 14a Kaiser RP, Hessler F, Mosinger J, Cisarova I, Kotora M. Chem. Eur. J. 2015; 21: 13577
- 14b Hashmi AS. K, Buhrle M, Salathe R, Bats JW. Adv. Synth. Catal. 2008; 350: 2059
- 14c Hamze A, Provot O, Alami M, Brion J-D. Org. Lett. 2005; 7: 5625
- 14d Mora-Radó H, Bialy L, Czechtizky W, Méndez M, Harrity JP. A. Angew. Chem. Int. Ed. 2016; 55: 5834
- 14e Buksnaitiene R, Urbanaite A, Cikotiene I. J. Org. Chem. 2014; 79: 6532
- 15a Nishida M, Shintani R. Chem. Eur. J. 2019; 25: 7475
- 15b Zhou F, Han X, Lu X. J. Org. Chem. 2011; 76: 1491
- 15c Ji K, Zheng Z, Wang Z, Zhang L. Angew. Chem. Int. Ed. 2015; 54: 1245
- 15d Wu X, Li M-L, Chen D-F, Chen S-S. J. Org. Chem. 2014; 79: 4743
- 15e Huple DB, Ghorpade S, Liu R-S. Chem. Eur. J. 2013; 19: 12965
- 15f Onishi Y, Iyoda M, Nakagawa M. Tetrahedron Lett. 1981; 22: 3641
For reviews, see:
For selected references, see:
For selected references, see:
For selected references, see:
