Triethylamine → 1-{(E,1R,3aS,7aS)-1-bromo-4-(bromomethylene)-octahydro-7a-methyl-1H-indene-1-yl}ethanone

Participants

Reaction Steps

1-{(E,3S,3aS,7aR)-7-(bromomethylene)-octahydro-3a-methyl-1H-indene-3-yl}ethanone (Compound 11: 100 mg, 0.369 mmol) was dissolved in methylene chloride (400 μl), and hexamethyldisilazane (160 μl, 0.758 mmol) and iodotrimethylsilane (80 μl, 0.562 mmol) were added thereto at −20° C., followed by stirring the resulting mixture for 10 minutes. The mixture was warmed to room temperature and stirred for another 100 minutes. The solvent was removed by evaporator, and the residue was dissolved in hexane. Saturated aqueous sodium hydrogen carbonate was added to the reaction solution and the resulting mixture was extracted with hexane. The combined organic layer was washed with saturated brine, dried over sodium sulfate, and evaporated to obtain a crude product of silylenol ether (143 mg). The obtained crude product was dissolved in tetrahydrofuran (700 μl), and a solution of triethylamine (50 μl, 0.359 mmol) and tetra-n-butylammonium tribromide (179 mg, 0.371 mmol) in tetrahydrofuran (400 μl) was added thereto at 0° C. After stirring the resulting mixture for 15 minutes, the mixture was warmed to room temperature and stirred for another 1 hour. The reaction solution was diluted with diethyl ether, and saturated aqueous sodium hydrogen carbonate was added thereto. The aqueous layer was extracted with diethyl ether. The combined organic layer was washed with aqueous sodium thiosulfate solution, aqueous potassium hydrogen sulfate solution and with saturated brine, and dried over sodium sulfate, followed by evaporation to obtain a crude product. The product was purified by flash column chromatography to obtain 1-{(E,1R,3aS,7aS)-1-bromo-4-(bromomethylene)-octahydro-7a-methyl-1H-indene-1-yl}ethanone as a white solid (99.2 mg, 76.9%).

Provenance & Evidence