Porcine liver esterase (PLE)- or rabbit liver esterase (RLE)-catalyzed hydrolysis of the pro-S ester group of diethyl α-alkyl-α-(benzyloxycarbonylamino)malonates 2a-c afforded (R)-ethyl α-alkyl-α-(benzyloxycarbonylamino)malonates 3a-c each in excellent enatiomeric excess. Enantiodivergent reductions of these acid esters 3a-c readily furnished both the corresponding enantiomeric α-substituted serines