Réactions du diazométhane III. Etude de la réaction d'insertion entre diazométhane et phénylcarbamates: comportement de la N-(phénoxy-carbonyl)-aniline et de la N-(p-nitrophénoxy-carbonyl)-aniline

Diazomethane reacts with N-(p-nitrophenoxy-carbonyl)-aniline giving on the one hand p-nitroanisole and phenylisocyanate, the latter being transformed into N-phenyl-β-propiolactam, and on the other hand N-(p-nitrophenoxy)-acetanilide by insertion. N-(phenoxy-carbonyl)-aniline does not react. The insertion reaction seems to depend on the heterolysis of the bond between the oxygen of the p-nitrophenoxy group and the carbamic carbonyl function, which is strongly polarized (existence of a mesomeric nitro-phenoxonium). The insertion is equally influenced y the nature of the radical R attached to the carbamic nitrogen: with R = ? CH₂COOC₂H₅ the reaction yields only isocyanate, with R = ? C₆H₅ it yields at the same time the isocyanate and the insertion product.