4-Toluenesulfonyl chloride → 6,6-Dimethyl-2-nitro-6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazine

Participants

Reaction Steps

To a solution of 139b (1.1 g, 5.1 mmol) in DMF (10 mL), was added NaH (60 percent dispersion in mineral oil, 246 mg, 6.14 mmol) at 0° C. The resulting suspension was stirred for 30 min, followed by the addition of p-toluenesulfonyl chloride (1169 mg, 6.14 mmol). The mixture was stirred at 60° C. overnight. After cooling to room temperature, saturated ammonium chloride solution was added and the mixture was extracted with dichloromethane. The combined organic layer was washed with brine, dried over Na2SO4, and evaporated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with petroleum ether/ethyl acetate gradient (9:1 to 2:1) to afford 139c (228 mg, 22%). MS-ESI: [M+H]+ 198.3

Provenance & Evidence