Reduction of the piperidine keto esters 16–19 using fermenting bakers' yeast provides high yields of the corresponding hydroxy esters 20, 26, 32 and 37 respectively, exclusively as the cis-diastereoisomers and with good levels (80%) of enantiomeric enrichment. The relative stereochemistries of the products were deduced from NMR data while the absolute configurations were determined by degradation to known piperidinemethanol derivatives ...