The mechanism for interconversion of stereoisomers in N-(2,3-dihydro-2-oxobenzoxazol-3-yl)- and N-(1,2-dihydro-2-oxoquinolin-1-yl)-N-1-methylallylarenesulphenamides

Abstract

Stereoisomers of the quinolone and benzoxazolinone-substituted sulphenamides (1) and (2) are interconverted by formal rotation around their N–N (chiral) axes. Two alternative pathways which could result in net rotation have been tested. Neither epimerisation at C-1 via a route involving [2,3] sigmatropic rearrangement nor radical dissociation–recombination have been found to contribute significantly to interconversion of the stereoisomers. The retarded rate of steroisomer interconversion in the 4-methylbenzoxazolinone-sulphenamide (16) by comparison with (2) suggests that this process in (2) occurs by simple N–N bond rotation and a similar conclusion has been drawn in the case of (1) by comparison with the rate of recemisation of (19).