Asymmetric desymmetrization of saturated and unsaturated meso-1,2-diols

An asymmetric desymmetrization of saturated and unsaturated cyclic and acyc lic meso-1,2-diols has been developed from the ene acetals, prepared from t he norbornene carboxyaldehyde and meso-1,2-diols. The intramolecular haloet herification of the ene acetals as a key step afforded 8-membered acetals i n a stereoselective manner just by the reaction of norbornene olefin even w hen the ene acetals from unsaturated meso-1,2-diols having olefins in the s ame molecule were used. Subsequent reductive elimination, followed by prote cting the hydroxy group and transacetalization, gave optically active 1,2-d iol derivatives and the starting ene acetals in good yields. (C) 2000 Elsev ier Science Ltd. All rights reserved.