3-(2-dimethylamino-ethyl)-1H-indole-5-carbaldehyde → 3-[2-(N,N-Dimethylamino)ethyl]-5-vinyl-1H-indole

Participants

Reaction Steps

To a solution of 3-(2-dimethylamino-ethyl)-1H-indole-5 carbaldehyde (Example 13) (0.216 g, 1 mmol) in THF (5 mL), methyl triphenyl phosphonium bromide (0.393 g, 1.1 mmol) is added. To the obtained slurry, under an argon atmosphere potassium tert-butoxide (0.118 g, 1.05 mmol) is added in three portions at ambient temperature. When thin layer chromatography (TLC) indicates complete conversion of the aldehyde, the mixture is poured on ice and extracted with ethyl acetate. Removal of the solvent gives a residue which is chromatographed on silica (25 g, CHCl3, MeOH, NEt3 19:1:0.5 v:v:v) to give the title product as pale yellow oil (0.190 g, 88%). 1H-NMR (CDCl3, 300 MHz) δ 2.37 (s, 6H, N(CH3)2); 2.64-2.70 (m, 2H, CH2NMe2); 2.92-2.99 (m, 2H, CH2); 5.13 (d, 1H, J=10.9 Hz, cis H2C═CH); 5.69 (d, 1H, J=17.6 Hz, trans H2C═CH); 6.84 (dd, 1H, H2C═CH); 6.94 (br s, 1H, H-2); 7.24 (d, 1H, J=8.2 Hz, H-7); 7.31 (dd, J=1.8 Hz, H-6); 7.58 (d, 1H, H-4); 8.66 (br s, 1H, NM). 13C-NMR (CDCl3, 75 MHz) δ 24.00 (CH2); 45.73 (N(CH3)2); 60.62 (CH2NMe2); 110.93 (H2C═CH); 111.50 (C-7); 114.66 (C-3); 117.41 (C-4); 120.20 (C-6); 122.42 (C-2); 127.83 (C-5); 129.34 (C-9); 136.45 (C-8); 138.22 (H2C═CH).

Provenance & Evidence