Temperature-controlled regioselectivity in the reductive cleavage of p-methoxybenzylidene acetals

Results reveal that the reductive cleavage of anisylidene acetals by BH3/Bu2BOTf can selectively produce either regioisomer, simply by adjusting the reaction temperatures and reagent concentrations. Reductive ring opening at low temperatures is determined to be compatible with sensitive functional groups such as allyl and enol ethers and other ketals.