A practical process for the preparation of tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo[1,2-c][1,3,2]oxazaborole-borane. A highly enantioselective stoichiometric and catalytic reducing agent

A practical, large-scale process for the preparation of tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo-[1,2-c][1,3,2]oxazaborole-borane is reported. The title compound is a stable, free-flowing crystalline solid useful either stoichiometrically or catalytically for the enantioselective reduction of prochiral ketones. When used stoichiometrically to reduce acetophenone the enantioselectivity is greater-than-or-equal-to 99.8% ee.