Asymmetric Desymmetrization of 4,5-Epoxycyclohex-1-ene by Enantioselective Allylic Oxidation

Asymmetric desymmetrization of allylic oxidation of 4,5-epoxycyclohex-1-ene (1) took place in the presence of 2.5 mol % of Cu(CH₃CN)₄PF₆ and 3 mol % of chiral N,N-bidentate ligand (S)-2 to afford (3S,4S,5S)-3-benzoyloxy-4,5-epoxycyclohex-1-ene (3) in 84% ee, which was increased up to >99% ee after recrystallization of 3-4′-nitrobenzoyloxy derivative 6. Optically pure 6 proved to be a key intermediate for enantioselective synthesis of O-protected 2-deoxystreptamine (2-DOS) precursor 12.