Hydrazine hydrate (1:1) → 6-Bromo-4-methyl-7-trifluoromethyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one

Participants

Reaction Steps

A mixture of ethyl 2-(6-bromo-3-oxo-7-(trifluoromethyl)-2H-benzo[b][1,4]oxazin-4(3H)-yl)propanoate (7.7 g, 19.44 mmol) and Lawesson reagent (8.65 g, 21.38 mmol) in toluene (20 mL) was heated at reflux for 1 h. The reaction mixture was cooled to ambient temperature, hydrazine hydrate (4.98 g, 155 mmol) was added and the reaction mixture was heated at 80° C. for 1 h. The reaction mixture was cooled to ambient temperature and the solvent was evaporated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 16-33% EtOAc in petroleum ether) to give 6-bromo-4-methyl-7-trifluoromethyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one as white solid (1.30 g, 18%). 1H NMR (DMSO-d6, 400 MHz): δ 10.92 (s, 1H), 7.66 (s, 1H), 7.34 (s, 1H), 4.88 (q, J=6.8 Hz, 1H), 4.72 (d, J=13.2 Hz, 1H), 4.64 (d, J=13.2 Hz, 1H), 1.30 (d, J=6.8 Hz, 3H).

Provenance & Evidence