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

Participants

Reaction Conditions

Reaction Steps

To a mixture of 5-bromo-4-(4-(4-fluorobenzyl)piperazin-1-yl)-3-nitropyridin-2-amine (0.120 g, 0.30 mmol) and EtOH (5 mL), was added p-anisaldehyde (0.045 g, 0.33 mmol) in EtOH (1.8 mL), followed by a freshly prepared aqueous solution of Na2S2O4 (1M; 0.9 mL, 0.9 mmol). The reaction mixture was heated at 85° C. for 24 h, then allowed to cool to room temperature and the solvents were removed in vacuo. The residue was absorbed on silica gel and purified by column chromatography on a Biotage SP1 system eluting with methanol (2-10%) in dichloromethane. The title compound was isolated as a pale yellow solid after trituration with diethyl ether (0.010 g, 7%); 1H-NMR (500 Mz, DMSO-d6): δ 2.60 (m, 4H, piperazine N(CH2)2), 3.56 (s, 2H, NCH2), 3.65 (m, 4H, piperazine N(CH2)2), 3.84 (s, 3H, OMe), 7.10 (d, J=7.0 Hz, 2H, ArH, C6H4—OMe), 7.17 (br t, J=9.0 Hz, 2H, ArH, C6H4—F), 7.40 (br dd, J=8.5, 6.0 Hz, 2H, ArH, C6H4—F), 8.13 (d, J=9.0 Hz, 2H, ArH, C6H4—OMe), 8.20 (s, 1H, imidazo[4,5-b]pyridine 5-H), 13.34 (br s, 1H, imidazo[4,5-b]pyridine N—H); LC (Method B)-MS (ESI, m/z) 3.58 min—496/498 [(M+H)+, Br isotopic pattern]. ESI-HRMS: Found: 496.1144, calculated for C24H24BrFN5O (M+H)+: 496.1148.

Provenance & Evidence