To a mixture of 5-bromo-4-[4-(4-chloro-benzyl)-piperazin-1-yl]-3-nitro-pyridin-2-ylamine (0.051 g, 0.12 mmol) and EtOH (3 ml) was added 4-methoxybenzaldehyde (0.026 g, 0.18 mmol) with the aid of EtOH (1 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 18 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 and elution with a gradient of methanol (0 to 3%) in ethyl acetate/dichloromethane (v:v; 2:3) afforded a pale yellow solid. The title compound was obtained as a white solid after trituration with diethyl ether (0.026 g, 42%). 1H-NMR (500 MHz, DMSO-d6) 2.60 (br s, 4H, piperazine N(CH2)2), 3.57 (s, 2H, NCH2—C6H4Cl), 3.66 (br s, 4H, piperazine N(CH2)2), 3.84 (s, 3H, OCH3), 7.10 (d, J=8.1 Hz, 2H) and 8.13 (d, J=8.1 Hz, 2H) (3,5-C6H4OMe and 2,6-C6H4OMe), 7.41 (m, 4H, C6H4Cl), 8.20 (s, 1H, imidazo[4,5-b]pyridine 5-H), 13.37 (br s, 1H, imidazo[4,5-b]pyridine N—H);
