Reduction of esters to alcohols and iodides using aminodiborane (-NH₂B₂H₅): scope and mechanistic investigations

Herein, we report an efficient methodology for the reduction of esters, carbonates, and anhydrides to alcohols using in situ generated aminodiborane from iodine and ammonia borane. This methodology also finds use for the transformation of esters to iodides by varying the stoichiometry of reagents. The protocol has broad substrate scope for transformation of esters to alcohols and iodides with excellent yields. The method is also useful for synthesizing pharmaceutically and industrially important compounds such as a Cinacalcet precursor, a Streptoindole analogue, and 1,4-pentanediol. Control studies and DFT calculations carried out to study the reduction mechanism of esters using aminodiborane indicate that a dioxaborinamine intermediate is formed during the reaction.