Trifluoroacetic acid → (4s,7r)-2-(2-Chloro-4-fluoro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one

Participants

Reaction Conditions

Reaction Steps

Trifluoroacetic acid (50 mL) was added in two portions to a cooled (0° C.) solution of N′-(2-chloro-4-fluoro-phenyl)-N′-((1R,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (14.8 g, 33.7 mmol) in dichloromethane (50 mL). The mixture was stirred at 0° C. for 5 min and then the cooling bath was removed and the reaction mixture was allowed to warm to room temperature and stir for 4 h. Volatiles were evaporated under reduced pressure and dichloromethane (250 mL) was added. The solution was washed with water (4×125 mL), and brine (125 mL), dried (magnesium sulfate), filtered, and evaporated. The flask containing the product was covered in foil and the solid was dried overnight under high vacuum to give (4S,7R)-2-(2-chloro-4-fluoro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (11.4 g, 105% of the expected amount). This material was used in subsequent reactions without further purification.

Provenance & Evidence