Stereoselective Reduction of Dicarboxylic Esters using NaBH₄-InCl₃

Significance

gem-Dicarboxylic esters in the presence of a lactam moiety were reduced diastereoselectively to the monoalcohol using a catalytic amount of NaBH₄ and InCl₃. The presence of the lactam group was necessary for an efficient reaction as the absence of the carbonyl moiety on the lactam produced slower reactions in poorer yields. The proposed mechanism involves dichlo­roindium hydride generated in situ from NaBH₄ and a catalytic amount of InCl₃, resulting in a stereoselective radical decarboxylation, followed by reduction of the ester to give the monoalcohol.