Reactivity of Some Intramolecular Aza-Wittig Reactions

Abstract

The reactivity of intramolecular aza-Wittig type reactions of some selected ω-azido carbonyl compounds [2], [4] as well as ω-chloro acyl azides [ 6 ], was described. The starting azides were readily obtained by nucleophilic substitution reactions of the coesponding chlorides with NaN₃ under the phase-transfer-catalyzed conditions, and by the Michael addition reactions of HN₃ to α, β-unsaturated ketones.
The intramolecular aza-Wi ttig reactions proceeded readily for γ-azido ketone [2 c], and even for razido ester[2 d] and γ-chloro acyl azide [6 b], to give pyrroline, pyrrolidine systems respectively. On the other hand, the corresponding intramolecular reactions of [ 4], [2 b] and [6 a] to azetine, azetidine systems did not proceed under vigorous conditions. However, 2-phenyl-1-azetin [18] was given in very lower yield by the reaction of β-azidopropiophenone[2 a] with PPh₃, that was confirmed by an alternative synthesis from 1-phenylcyclopropyl azide [23] and by conversion to the corresponding azetidine [19].