Benzyl Bromide → (4r,7s)-1-Benzyl-2-(2,4-difluoro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one

Participants

Reaction Conditions

Reaction Steps

A solution of (4R,7S)-2-(2,4-difluoro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (Intermediate 42; 213 mg, 0.7 mmol), tetrabutylammonium iodide (271 mg, 0.7 mmol) and benzyl bromide (0.45 mL, 3.7 mmol) in dimethylformamide (1.4 mL) was heated at 100° C. in a sealed tube for 24 h and then left at room temperature for a further 24 h. The solvent was evaporated and ethyl acetate was added. The solution was washed with 10% aqueous sodium thiosulfate and brine, dried (sodium sulfate), filtered, evaporated, and purified using an Analogix Intelliflash 280 system (Analogix, Inc. Burlington, Wis.) with a RS-12G silica gel column, eluting with 10-100% ethyl acetate/hexanes, to give a light brown foam. This was dissolved in ethanol and the solution was treated with activated carbon (15 mg) and heated at 50° C. for 1 h. The mixture was filtered through Celite and the Celite was washed with ethanol. The combined filtrates were evaporated and the resulting foam was dried under high vacuum to give (4R,7S)-1-benzyl-2-(2,4-difluoro-phenyl)-7,8,8-trimethyl-1,2,4,5,6,7-hexahydro-4,7-methano-indazol-3-one (220 mg, 80%) as an off-white solid. ES(+)-MS (M+H) 395.

Provenance & Evidence