Skeletal rearrangements in the nitrations of α,β-unsaturated esters
作者:Stuart A Hewlins、John A Murphy、Jian Lin
DOI:10.1016/0040-4039(95)00421-8
日期:1995.4
Reaction of α,β-unsaturated esters with nitroniumtetrafluoroborate in acetonitrile at −16°C affords products of skeletal cationic rearrangements suggesting the intermediacy of highly reactive α-carbonyl cations.
Nitration of α,β-unsaturated esters. Evidence for positive charge build-up adjacent to carbonyl carbon
作者:Stuart A. Hewlins、John A. Murphy、Jian Lin、David E. Hibbs、Michael B. Hursthouse
DOI:10.1039/a607170h
日期:——
Reactive intermediates formed in the nitration of certain
α,β-unsaturated esters with nitronium tetrafluoroborate
exhibit behaviour expected of highly reactive α-carbonyl cations.
Three diagnostic reaction types have been observed which indicate the
presence of these destabilised cations: (i) trapping in a Ritter
reaction, (ii) cyclopropane formation from propyl cations, (iii)
WagnerâMeerwein migration of alkyl groups. Semi-empirical
calculations of the relative gas-phase stabilities of the proposed
intermediate cations are useful in rationalising the observed
chemistry.