A Selectivity Study of Activated Ketal Reduction with Borane Dimethyl Sulfide

Article abstract of DOI:10.1021/jo00076a041

A chemo- and regioselectivity study of the reagent combination BH3*SMe2/TMSOTf for ketal reduction has been undertaken.It has revealed that simple 1,3-dioxanes reduce cleanly at low temperature in CH2Cl2 while simple 1,3-dioxolanes may give complete ring cleavage and dimerization products.A study of reduction of 4-substituted 1,3-dioxolanes has revealed a solvent-directed regioselectivity which in THF favors the secondary protected derivative.A mechanism is postulated to account for the selectivities based on recent thinking on acetal substitution reactions.