The cyclization of some methylphenylhydrazones to indoles. The preparation of some polymethine dyes related to Astrazon Orange R

Abstract

The cyclization of several substituted acetophenone methylphenylhydrazones to indoles has been achieved by means of polyphosphoric acid as the reagent. The resultant N-methyl-2- phenylindoles and their 3-formyl analogues were used for the preparation of several new polymethine basic dyes related to Astrazon Orange R, the ultraviolet spectral and lightfastness (on wool) properties of which are described. The cyclization of some cycloalkanone methylphenylhydrazones has been achieved in acetic acid.