For the synthesis of metalloproteinase inhibitors the (R, R)-and (S, S)-monoethyl esters of N- Boc-pyrrolidine-3, 4-dicarboxylic acid were prepared as key intermediates from the trans- diester racemate by two consecutive, highly selective enzymatic reactions. Reduction of the formed acids to the corresponding enantiopure hydroxymethyl derivatives ((R, R)-and (S, S)- ethyl N-Boc-4-hydroxymethyl-3-carboxylate) gives access to a new series of chiral ...