Preparation of (S)-N-Substituted 4-Hydroxy-pyrrolidin-2-ones by Regio- and Stereoselective Hydroxylation with Sphingomonas sp. HXN-200

[reaction: see text] Enantiopure (S)-N-substituted 4-hydroxy-pyrrolidin-2-ones have been prepared for the first time by regio- and stereoselective hydroxylation of the corresponding pyrrolidin-2-ones by use of a biocatalyst. Hydroxylation of 6 and 8 with Sphingomonas sp. HXN-200 afforded 68% of (S)-7 in >99.9% ee and 46% of (S)-9 in 92% ee, respectively. Simple crystallization increased the ee of (S)-9 to 99. 9% in 82% yield.