A chemoenzymatic process for the stereoselective preparation of both the (R) and (S) enantiomers of 3-hydroxy-3-(2-thienyl) propanenitrile has been developed. These optically pure key intermediates were prepared by enzymatic resolution of ()3-hydroxy-3-(2-thienyl) propanenitrile both by transesterification and by hydrolysis reaction which were then transformed to both enantiomers of duloxetine.