Hydroboration of tricarbonylironergosteryl benzoate. Synthesis of (22R)- and (22S)-3β-benzoyloxyergosta-5,7-dien-22-ol and (23R)-3β-benzoyloxyergosta-5,7-dien-23-ol

Abstract

Hydration of tricarbonylironergosteryl benzoate via hydroboration and subsequent decomplexing affords a mixture of (22R)- and (22S)-3β-benzoyloxyergosta-5,7-dien-22-ol and (23R)-3β-benzoyloxyergosta-5,7-dien-23-ol. Oxidation gives 3β-benzoyfoxyergosta-5,7-dien-22- and -23-one. On reduction these ketones yield (23S)-3β-benzoyloxyergosta-5,7-dien-23-ol in addition to the above three dienols. Stereochemical assignments are on the basis of molecular rotations.