Oxidative cyclizations. VII. Cyclization of 2-substituted anilines with alkaline hypohalite

Abstract

The Green-Rowe oxidation of 2-nitroanilines with alkaline hypochlorite, to yield benzofuroxans, is demonstrated by studies of the visible spectra of transient intermediates to proceed through N-chlorination and a singlet nitrene. Two variations on the route to the nitrene are possible. The cyclization step is represented as an internal capture of the nitrene by the ortho substituent, and on this basis the Green-Rowe oxidative cyclization is now extended to anilines whose ortho substituent is benzoyl or phenylazo. It is not however successful for ortho phenyl. Azo compounds were observed as byproducts in some of these reactions, and are shown to arise via N,N-dichloroanilines.