Biotin – The Chiral Challenge

In this contribution, the first examples of the catalytic highly enantioselective reduction of cyclic meso-anhydrides to lactones and of thioanhydrides to thiolactones are described. The N-benzyl protected key building blocks in the industrial synthesis of (+)-biotin were so far only accessible by usage of expensive reagents in multi-step procedures. In contrast, homogeneous catalytic enantioselective hydrogenation of the corresponding meso-anhydride mediated by a metal phosphane complex proceeds with high optical induction (ee >95%) and excellent yield. The catalytic system provides a generally applicable new method for the preparation of lactones from cyclic anhydrides.