A New Target for Highly Stereoselective Katsuki–Sharpless Epoxidation – One‐Pot Synthesis of C 2 ‐Symmetric 2,2′‐Bioxiranes

The double asymmetric Katsuki–Sharpless epoxidation of a conjugated diallyl alcohol affords excellent enantioselectivity (>97 % ee ), the product being isolated as the stable p ‐nitrobenzoate 5a or tosylate 5b . The optical purities of the chiral epoxides were determined by HPLC on chiral columns, while the molecular structures of compounds 5a and 7 and the absolute configuration of mono‐epoxide 12 were confirmed by X‐ray crystallography. Possible π–π stacking interaction has been evaluated by ab initio calculation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)