Ketenimines as intermediates to heterocycles. Part 3. Rearrangement of 3-iminoisoxazolines to 2-imino-oxazolines

Abstract

N-Substituted hydroxylamines (2) add to 2-benzoyl-N,2-diphenylvinylideneamine (1) and the adducts are easily dehydrated to give the 3-iminoisoxazolines (4). Compounds (4) with 2-aryl substituents rearrange spontaneously to give the 2-imino-oxazolines (5) or (6), but the 2-methyl derivative is more stable and only rearranges on heating. 2-Imino-3-acylaziridines (8) or (9) are assumed to be the intermediates; the expected 2-imino-oxazoline (5b) was isolated among the products during an attempted synthesis of 1,3-diphenyl-2-phenylimino-3-benzoylaziridine (8b) from benzoylphenylcarbene and diphenylcarbodi-imide.