Cascade Nucleophilic Addition–Cyclic Michael Addition of Arynes and Indoles Bearing Michael Acceptor: A Strategy to Construct Pyrroloacridines and Study of Their Physicochemical Properties

Abstract

A facile synthetic approach to 6H-pyrrolo[3,2,1-de]acridines has been developed by using cascade N-nucleophilic addition−cyclic Michael addition process of arynes and indoles substituted with Michael acceptors under metal-free conditions. Additionally, photophysical studies of a few of the newly synthesized pyrroloacridine compounds indicated good fluorescence emission properties.

Diastereoselective Synthesis of Pyrroloquinolines via N–H Functionalization of Indoles with Vinyl Sulfonium Salts

“…■ EXPERIMENTAL SECTION General Information. 1 H and 13 C NMR spectra were recorded on Varian 400 MHz spectrometers. Chemical shifts (δ) were reported in ppm downfield from CDCl 3 (δ = 7.26 ppm) or DMSO-d 6 (δ = 2.50 ppm) for 1 H NMR and relative to the central CDCl 3 resonance (δ = 77.0 ppm) or DMSO-d 6 (δ = 39.5 ppm) for 13 C{ 1 H} NMR spectroscopy.…”

“…The product 3ca was obtained as a white solid (45.6 mg, 95% yield) via flash chromatography on a silica gel (petroleum ether/ethyl acetate = 20:1, v/v); 1 H NMR (400 MHz, DMSO- [c]pyrrolo[3,2,1-ij]quinolin-4-yl)ethan-1-one (3ea). The product 3ea was obtained as a yellow solid (47.2 mg, 92% yield) via flash chromatography on a silica gel (petroleum ether/ethyl acetate = 20:1, v/v); 1 H NMR (400 MHz, CDCl 3 ) δ (ppm): 8.17 (d, J = 8.0 Hz, 1H), 8.0 (d, J = 8.0 Hz, 2H), 7.97 (s, 1H), 7.72 (d, J = 8.0 Hz, 2H), 7.44 (d, J = 7.2 Hz, 1H), 7.37 (t, J = 8.6 Hz, 1H), 7.34−7.32 (m, 2H), 7.26−7.25 (m, 3H), 5.03 (d, J = 13.6 Hz, 1H), 4.43 (d, J = 13.6 Hz, 1H), 3.88 (d, J = 4.8 Hz, 1H), 3.37 (d, J = 4.8 Hz, 1H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ (ppm): 192.6, 175.0 (q, J = 35.1 Hz), 140.3, 136.7, 135.4 (q, J = 4.8 Hz), 134.5 (q, J = 32.5 Hz), 131.3, 129.1, 128.9, 128.4, 125.8 (q, J = 3.7 Hz), 124.8, 124.7, 123.5 (q, J = 271.3 Hz), 122.2, 121.0, 120.7, 117.0 (q, J = 289.2 Hz), 111.6, 48.9, 42.6, 40.4, 27.2; 19…”

“…The product 3la was obtained as a yellow solid (38.9 mg, 81% yield) via flash chromatography on a silica gel (petroleum ether/ethyl acetate = 20:1, v/v); 1 H NMR (400 MHz, CDCl 3 ) δ (ppm): 8.15 (d, J = 8.0 Hz, 1H), 7.9 (s, 1H), 7.48−7.43 (m, 3H), 7.41−7.38 (m, 5H), 7.36−7.28 (m, 3H), 5.05 (d, J = 13.6 Hz, 1H), 4.39 (d, J = 13.6 Hz, 1H), 3.76 (d, J = 4.8 Hz, 1H), 3.34 (d, J = 4.8 Hz, 1H); 13…”

“…The product 3ma was obtained as a yellow solid (37.5 mg, 79% yield) via flash chromatography on a silica gel (petroleum ether/ ethyl acetate = 20:1, v/v); 1 H NMR (400 MHz, CDCl 3 ) δ (ppm): 8.13 (d, J = 8.0 Hz, 1H), 7.94 (s, 1H), 7.53 (d, J = 7.6 Hz, 1H), 7.46 (t, J = 7.6 Hz, 1H), 7.41−7.37 (m, 3H), 7.35−7.28 (m, 4H), 6.98 (t, J = 8.0 Hz, 1H), 6.97 (d, J = 8.8 Hz, 1H), 4.97 (d, J = 13.6 Hz, 1H), 4.41 (d, J = 13.2 Hz, 1H), 3.99 (s, 3H), 3.78 (d, J = 5.2 Hz, 1H), 3.40 (d, J = 5.2 Hz, 1H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ (ppm): 195.1, 175.0 (q, J = 34.2 Hz), 158.5, 137.7, 135.0 (q, J = 5.2 Hz), 133.9, 131. 4…”

“…The product 3va was obtained as a yellow solid (37.2 mg, 71% yield) via flash chromatography on a silica gel (petroleum ether/ethyl acetate = 20:1, v/v); 1 H NMR (400 MHz, DMSO- Hz, 2H), 7.32−7.26 (m, 6H), 7.16 (t, J = 7.6 Hz, 1H), 7.10 (s, 1H), 4.82 (d, J = 12.8 Hz, 1H), 4.15 (d, J = 12.4 Hz, 1H), 3.78 (d, J = 4.4 Hz, 1H), 3.58 (d, J = 4.8 Hz, 1H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ (ppm): 194.1, 138.0, 137.7, 133.0, 130.9, 129.0, 128.8, 128.6, 128.1, 127.9, 123.7, 123.3, 121.0, 120.9, 120.0, 116.5, 107.2, 48.2, 43.3, 39.0, 27.2; ESI-HRMS: [M + H] + calcd. for C 25 H 19 ClNO + 384.1150, found 384.1150.…”