Studies of regio- and stereoselectivity in some nucleophilic ring opening reactions of N-tosyl-3-phenyl-2-aziridinemethanols and derivatives

Abstract

A study has been made of the regio-and Stereoselectivity of the ring opening reactions of the 3-aryl substituted aziridines 1 and 2. The regiochemical outcome is apparently decided by a balance of electronic activation at C-3 by the phenyl group and the chelating effects of C-1 oxygen functionality which can direct nucleophiles intramoleculary to C-2 or C-3. Good levels of regiocontrol for either C-3 or C-2 attack are obtained particularly for the reactions of aziridino alcohols 1a and 2a with hydride reagents, while methyl-transfer reagents such as LiMe 2Cu and AlMe 3 tend to give exclusive C-3 attack with inversion (cuprate) or inversion plus retention (trialkylaluminum). Possible reaction mechanisms (inter-vs. intramolecular) are discussed.