(Diethylamino)sulfur trifluoride → 7-Bromo-3-fluoro-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one

Participants

Reaction Steps

A well stirred suspension of 6.0 g (0.018 mole) of 7-bromo-1,3-dihydro-3-hydroxy-5-phenyl-2H-1,4-benzodiazepin-2-one in 250 ml methylene chloride was cooled to -70°, and 7.5 ml (0.06 mole) of diethylaminosulfur trifluoride was added dropwise. The reaction mixture was allowed to warm slowly to -10° over a period of 30 min., and held at -10° for 20 min., until most of the solid had dissolved. The reaction mixture was poured into 500 ml of ice water and stirred until the yellow color faded. The organic layer was separated, dried over MgSO4, and evaporated to dryness under reduced pressure. The residue was dissolved in 300 ml of hot benzene and filtered hot. The filtrate was mixed with 400 ml hexane and cooled. The crystals that separated were collected on a filter, washed with hexane, and dried in air to give 5.28 g (88%) of 3-fluoro-7-bromo-1,3-dihydro- 5-phenyl-2H-1,4-benzodiazepin-2-one as colorless crystals: mp 207°-209° (dec.); 19F nmr (acetone-d6) δ -162.6 ppm (d, J = 57 Hz); 1H nmr (acetone-d6) δ 5.86 ppm (d, J = 57 Hz, 1H), 7.2-8 ppm (m, 8H), 9.90 ppm (NH); ir (KBr) 5.84μ (C=O). A sample was dried in a vacuum oven for analysis.

Provenance & Evidence