Dynamic stereochemistry of imines and derivatives. Part 11. Synthesis and stereochemistry of (E)- and (Z)-nitrones

Abstract

A range of hindered nitrones [ArCR:N(O)R′; R = H or alkyl] has been synthesized and their stereochemistry has been assigned. The relative proportions of (E)- and (Z)-nitrone isomers at equilibrium were found to be both substituent- and solvent-dependent. The mechanism of the oxidation of imines to nitrones by peroxy-acid is discussed in relation to the reactant and product stereochemistry. The acidic hydrolysis of N-(pentamethylphenyl-methylene)alkylamine N-oxides has been used as a general synthesis of N-alkylhydroxylamines.