Epoxidation of Primary and Secondary Alkenylammonium Salts with Dimethyldioxirane, Methyl(trifluoromethyl)dioxirane, and m-Chloroperbenzoic Acid. A General Synthetic Route to Epoxyalkylamines

Article abstract of DOI:10.1021/jo00117a020

Selective syn-epoxidation of C=C double bonds in primary and secondary alkenylammonium arenesulfonate salts 3H(+), to give the corresponding epoxyalkylammonium salts 4H(+), has been achieved by reaction with electrophilic O-transfer reagents such as m-CPBA, methyl(trifluoromethyl)dioxirane (TFDO), and dimethyldioxirane (DMDO).Epoxyalkylamines 4 are easily obtained in high yields from the corresponding epoxyalkylammonium salts 4H(+) by simple deprotonation with sodium carbonate.The ammonium group deactivates the C=C double bond, and hence the epoxidation rate is slower than in the case of simple olefins.H-Bonding interaction between the ammonium group and the O-transfer reagent (m-CPBA and DMDO) in the transition state is claimed to account for the rate enhancement and diastereoselectivity observed when the necessary conformational requirements are established.The allylic ammonium group is shown to be very efficient in directing the epoxidation with m-CPBA and DMDO on the syn-diastereoface.