A hydrogen-bonded model for the syn epoxidation of cyclic allylic ethers under Payne conditions

The syn selectivity observed for the Payne (PhCNH2O2) epoxidation of cyclohexenyl ethers is consistent with an hydrogen-bonded model implying the allylic ether oxygen and the imino hydrogen of the in situ generated perbenzimidic acid. The geometry of the two most stable conformers, deduced from AM1 calculations, allows both hydrogen bonding and oxygen transfer.