(R)-2-Methyl-CBS-oxazaborolidine → (S)-1-{(3aS,7E,7aR)-7-(bromomethylene)-3a,4,5,6,7,7a-hexahydro-3a-methyl-1H-indene-3-yl}ethanol

Participants

Reaction Steps

1-{(3aS,7E,7aR)-7-(bromomethylene)-3a,4,5,6,7,7a-hexahydro-3a-methyl-1H-indene-3-yl}ethanone (Compound 13: 24.7 mg, 0.0918 mmol) was dissolved in toluene (200 μl), and (R)-2-methyl-CBS-oxazaborolidine (18 μl, 0.018 mmol, 1.0 M in toluene) and borane dimethyl sulfide (26 μl, 0.274 mmol) were added thereto at −20° C., followed by stirring the resulting mixture for 1 hour. Methanol (100 μl) was added to the reaction solution, and when generation of hydrogen gas stopped, diethyl ether and water were added thereto. After separating the organic layer, the aqueous layer was extracted with diethyl ether. The combined organic layer was washed with saturated brine, dried over sodium sulfate, and evaporated. The obtained crude product was purified by flash column chromatography to obtain (S)-1-{(3aS,7E,7aR)-7-(bromomethylene)-3a,4,5,6,7,7a-hexahydro-3a-methyl-1H-indene-3-yl}ethanol (23.6 mg, 94.8%) as a white solid. The spectrum data thereof agreed with the data described in Example 4.

Provenance & Evidence