Efficient general synthesis of 1,2- and 1,3-Diols in high enantiomeric excess via the intramolecular asymmetric reduction of the corresponding ketoalkyl diisopinocampheylborinate intermediates

Article abstract of DOI:10.1016/S0040-4039(96)02447-1

The first successful asymmetric reduction of unhindered aliphatic ketones with B-chlorodiisopinocampheylborane is reported. In contrast to the reduction in high ee of aralkyl ketones, such as acetophenone, with the reagent, the reduction of unhindered dialkyl ketones, such as 3-methyl-2-butanone, provides only poor ee. However, treatment of α- and β-hydroxyketones with one equiv of diisopnocampheylborane or B-chlorodiisopinocampheylborane rapidly produces the corresponding ketoalkyl diisopinocampheylborinate intermediates, which then undergo facile intramolecular reduction. This reaction sequence, followed by oxidative workup, provides a general synthesis of 1,2- and 1,3-diols in 84≤99% enantiomeric excess.