Acetohydrazide → 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepine

Participants

Reaction Steps

A solution of 7-bromo-3-methyl-4,5-dihydro-1H-benzo[b][1,4]diazepine-2(3H)-thione (1.5 g, 5.5 mmol) and acetohydrazide (693 mg, 9.36 mmol) in n-butanol (20 mL) was heated at 130° C. for 12 hours. The reaction mixture was concentrated in vacuo, diluted with water (20 mL), extracted with ethyl acetate (15 mL×3) and washed with brine (10 mL×3). The combined organic phase was dried over anhydrous sodium sulfate and then filtered. The filtrate was concentrated to give a crude product, which was purified by column chromatography (silica gel, dichloromethane/methanol=20:1) to afford 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepine, 5,6-dihydro-1,4-dimethyl-8-bromo as a white solid (1 g, 62%). 1H NMR (300 MHz, CDC13): δ 7.19-7.14 (m, 2H), 7.01 (d, J=8.1 Hz, 1H), 3.74-3.64 (m, 1H), 3.43-3.36 (m, 1H), 3.13-3.05 (m, 1H), 2.49 (s, 3H), 1.50 (d, J=6.9 Hz, 3H). LRMS (M+H)+: calcd 292.03. found 292.

Provenance & Evidence