Visible light-induced N-methyl activation of unsymmetric tertiary amines

Aerobic Oxidative EDA Catalysis: Synthesis of Tetrahydroquinolines Using an Organocatalytic EDA Active Acceptor

“… 47 Complete selectivity toward addition of methyl radicals to the Michael acceptors was observed when different N -Me- N -alkyl anilines were subjected to the reaction conditions, providing compounds 3x and 3y , consistent with the literature. 20 , 48 The sterically hindered o -methyl-DMA also resulted in lower reactivity ( Scheme 3 , entry 3v ). When N , N -diethyl aniline was subjected to the reaction conditions, no annulation product could be observed ( Scheme 3 , entry 3z ).…”

“…As a starting point for the study, N-substituted maleimides were chosen as reaction partners due to their well-known reactivity with aromatic α-amino alkyl radicals, forming tetrahydroquinolines under a range of reaction conditions. ,− The photochemically driven annulation reaction between DMA 1a and N -phenyl maleimide ( 2a ) to furnish tetrahydroquinoline ( 3a ) proceeded smoothly without an external photocatalyst under UV irradiation . However, the initial screening of reaction conditions, presented in Table , shows that visible light irradiation (with a white compact fluorescent lamp) in the absence of a catalyst resulted in a low yield.…”

“…Spectroscopic data were in accordance with the literature; 21 1 H NMR (400 MHz, chloroform-d): δ 7.68 (dd, J = 2.0, 0.9 Hz, 1H), 7.49− 7.40 (m, 2H), 7.40−7.31 (m, 2H), 7.30−7.21 (m, 3H), 6.67 (d, J = 8.5 Hz, 1H), 4.12 (dt, J = 9.6, 0.6 Hz, 1H), 3.63 (dd, J = 11.6, 2.8 Hz, 1H), 3.54 (ddd, J = 9.6, 4.4, 2.8 Hz, 1H), 3.17 (dd, J = 11.6, 4.4 Hz, 1H), 3.00 (s, 1H), 2.86 (s, 3H) ppm; 13 5-Benzyl-2-phenyl-3a,4,5,9b-tetrahydro-1H-pyrrolo[3,4-c]quinoline-1,3(2H)-dione (3x). 20 Starting with 40.5 mg of Nphenylmaleimide following the general procedure provided 3x as a yellow oil (36.6 mg, 42%) after purification using column chromatography (SiO 2 , 0−10% ethyl acetate in petroleum ether). Spectroscopic data were in accordance with the literature; 20 6, 175.9, 147.6, 137.8, 132.2, 130.7, 130.3, 129.2, 128.7, 128.7, 128.6, 127.5, 127.4, 126.5, 119.9, 119.0, 113.6, 55.5, 49.2, 44.3, 42.6 ppm.…”

“…20 Starting with 40.5 mg of Nphenylmaleimide following the general procedure provided 3x as a yellow oil (36.6 mg, 42%) after purification using column chromatography (SiO 2 , 0−10% ethyl acetate in petroleum ether). Spectroscopic data were in accordance with the literature; 20 6, 175.9, 147.6, 137.8, 132.2, 130.7, 130.3, 129.2, 128.7, 128.7, 128.6, 127.5, 127.4, 126.5, 119.9, 119.0, 113.6, 55.5, 49.2, 44.3, 42.6 ppm.…”

“…5-Allyl-2-phenyl-3a,4,5,9b-tetrahydro-1H-pyrrolo[3,4-c]quinoline-1,3(2H)-dione (3y). 20 Starting with 41.6 mg of Nphenylmaleimide following the general procedure provided 3y as a yellow oil (44.1 mg, 58%) after purification using column chromatography (SiO 2 , 0−10% ethyl acetate in petroleum ether). Spectroscopic data were in accordance with the literature; 20…”