Sodium Dithionite → 6-bromo-2-(4-methoxyphenyl)-7-(4-(pyridin-4-ylmethyl)piperazin-1-yl)-3H-imidazo[4,5-b]pyridine

Participants

Reaction Conditions

Reaction Steps

To a mixture of 5-bromo-3-nitro-4-(4-pyridin-4-ylmethyl-piperazin-1-yl)-pyridin-2-ylamine (0.047 g, 0.12 mmol) and ethanol (3.0 ml) was added 4-methoxybenzaldehyde (0.026 g, 0.18 mmol) with the aid of ethanol (1.0 ml), followed by a freshly prepared aqueous solution of Na2S2O4 (1M; 0.50 ml, 0.50 mmol). The reaction mixture was stirred at 70° C. for 8.5 h, then allowed to cool to room temperature and concentrated in vacuo. The residue was absorbed on silica gel, and the free-running powder was placed on a 10 g isolute silica column which was eluted with a gradient of methanol (0 to 4%) in ethyl acetate/dichloromethane (v/v; 1:1). The title compound was obtained as a pale yellow solid after trituration with diethyl ether (0.018 g, 31%). 1H-NMR (500 MHz, DMSO-d6) 2.63 (br s, 4H, piperazine N(CH2)2), 3.68 (br s, 4H, piperazine N(CH2)2), 3.62 (s, 2H, NCH2-pyridyl), 3.84 (s, 3H, OCH3), 7.10 (d, J=8.9 Hz, 2H) and 8.14 (d, J=8.8 Hz, 2H) (3,5-C6H4OMe and 2,6-C6H4OMe), 7.40 (d, J=5.9 Hz, 2H, pyridine 3-H and 5-H), 8.20 (s, 1H, imidazo[4,5-b]pyridine 5-H), 8.54 (d, J=5.9 Hz, 2H, pyridine 2-H and 6-H), 13.38 (br s, 1H, imidazo[4,5-b]pyridine N—H);

Provenance & Evidence