De Novo Synthesis of 2-Substituted syn-1,3-Diols via an Iterative Asymmetric Hydration Strategy

摘要

The enantioselective syntheses of several protected 4-substituted syn-3,5-dihydroxy carboxylic esters have been achieved from the corresponding achiral (E,E)-or (E,Z)-1,3-dienoates.The route relies upon an enantio-and regioselective Sharpless dihydroxylation and a palladium-catalyzed reduction to form gamma-substituted delta-hydroxy-1-enoates.The resulting delta-hydroxy-1-enoates are subsequently converted into benzylidene-protected 4-substituted syn-3,5-dihydroxy carboxylic esters in one step.The benzylidene-protected 3,5-dihydroxy carboxylic esters are produced in good overall yields (20-54%) and high enantiomeric excess (73-97% ee).