Abstract. The first regio-and stereospecific synthesis of S-(-)-13C-malic acid 5 with a high incorporation of 13C and excellent enantiomeric excess is described. S-(-)-13C-malic acid 5 was synthesized in a three-step reaction starting with ethyl acetate 2 and diethyl oxalate 1. The produced sodium diethyl oxaloacetate 3 was then enantioselectively reduced with bakers' yeast to S-(-)-13C-malic acid diethylester 4 which was hydrolyzed to S-(-)-13C- ...
