Sodium Dithionite → 6-Bromo-2-[4-(4-methyl-piperazin-1-yl)-phenyl]-7-[4-(1-phenyl-ethyl)-piperazin-1-yl]-3H-imidazo[4,5-b]pyridine

Participants

Reaction Conditions

Reaction Steps

To a mixture of 5-bromo-3-nitro-4-[4-(1-phenyl-ethyl)-piperazin-1-yl]-pyridin-2-ylamine (0.065 g, 0.16 mmol) and EtOH (7.5 ml) was added 4-(4-methyl-piperazin-1-yl)-benzaldehyde (0.042 g, 0.20 mmol) followed by a freshly prepared aqueous solution of Na2S2O4 (1M; 0.65 ml, 0.65 mmol). The reaction mixture was stirred at 80° C. for 20 h, then allowed to cool to room temperature, and concentrated in vacuo. The residue was absorbed on silica gel, the free-running powder was placed on a 10 g isolute silica column which was eluted first with 2% methanol in ethyl acetate/dichloromethane (v:v; 1:1) and then a gradient of methanol (2 to 8%) in chloroform. The titled compound was obtained as a brown solid after trituration with diethyl ether a (0.007 g, 8%). 1H-NMR (500 MHz, CD3OD) 1.55 (d, J=6.4 Hz, 3H, CHCH3), 2.50 (s, 3H, N—CH3), 2.80 (br s, 6H), 2.90 (br s, 2H), 3.42 (br s, 4H) and 3.80 (br s, 4H) (8× piperazine N(CH2)2), 3.70 (m, 1H, CHCH3), 7.10 (d, J=8.9 Hz, 2H) and 8.02 (d, J=8.7 Hz, 2H) (3,5-C6H4—N and 2,6-C6H4—N), 7.31 (t, J=7.2 Hz, 1H, PhH), 7.39 (t, J=7.6 Hz, 2H, PhH), 7.37 (d, J=7.2 Hz, 2H) (PhH), 8.20 (s, 1H, imidazo[4,5-b]pyridine 5-H);

Provenance & Evidence