A New Target for Highly Stereoselective Katsuki–Sharpless Epoxidation – One-Pot Synthesis ofC2-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)