Reactive intermediates from the solvolysis of mutagenic O-Alkyl N-acetoxybenzohydroxamates

Mutagenic O-(para-substituted benzyl)N-acetoxybenzohydroxamates undergo acid-catalysed solvolysis in aqueous acetonitrile but there is a change in mechanism from AA11 to E1 on going from para electron-withdrawing substituents to para+M electron-donating groups. The former permit the formation of a discrete nitrenium ion intermediate whereas the latter promote a concerted elimination of a resonance stabilized benzyl carbocation.