Electrochemical and stereochemical investigation on the mechanism of the decay of 2-halo amide anions. The intermediacy of aziridinones

Abstract

2-Halo amide anions can be generated by electroreduction of the corresponding NH-protic 2-halo amides through the self-protonation mechanism. Such anions are labile species whose decay, in the case of 2-bromo amide anions, competes with their electroreduction in the voltammetric time scale. Using the appropriate voltammetric treatment, the first-order rate constant of the decay has been determined for a series of representative 2-bromo amides. The lability orders point to an S N 2-the intramolecular substitution of bromine and thus to the formation of a three-membered ring. Stereochemical informationon the decay has been gained using a chiral nonracemic 2-bromopropanamide, an amine nucleophile, and DMF as the solvent