Trifluoroacetic acid → (4s,7r)-2-(2,5-Dichloro-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 (100 mL) was added slowly to a cooled (0° C.) solution of N′-(2,5-dichloro-phenyl)-N′-((1R,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]heptane-2-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (˜46.9 mmol) in dichloromethane (100 mL), and the resulting solution was stirred at 0° C. for 10 min and then at room temperature for 2 h. The solvent was evaporated and dichloromethane (200 mL) was added. The solution was washed with water (4×80 mL) and brine (80 mL), dried (magnesium sulfate), filtered, and evaporated to give a brown foam. This was triturated with 10% ethyl acetate/hexane (100 mL) and the mixture was stirred at room temperature for 20 min and then cooled in an ice-bath at 0° C. for 1 h. The solid was filtered off, washed with hexane, and dried to give (4S,7R)-2-(2,5-dichloro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (13.55 g, 86%) as a tan solid.

Provenance & Evidence