Resolution and Stereochemistry of tert-Butylphenylphosphinous Acid—Borane

摘要

A combined use of ephedrine and cinchonine as resolving agents enabled facile resolution of racemic tert-butylphenylphosphinous acid—borane (1) into the two enantiomers in ca. 31-32% yield each. The resolved 1 served as a model substrate to study stereoselective synthetic transformations of phosphinous acid—boranes yielding optically active phosphinite—borane, boranatophosphinous—sulfonic anhydride, secondary phosphine—borane, tertiary phosphine—borane, secondary phosphine oxide, and phosphinic halides. By the judicious choice of the reaction paths, either enantiomer of tert-butylphenylphosphine— borane and of tert-butylmethylphenylphosphine—borane could be stereoselectively obtained from a single enantiomer of 1.