The Fischer indolisation of cyclopropyl phenyl ketone and cyclobutyl phenyl ketone phenylhydrazones

Abstract

Reaction of cyclopropyl phenyl ketone (3) with an equimolar quantity of phenylhydrazine (6) in boiling ethanolic hydrogen chloride under reflux affords 2,3,4,5-tetrahydro-2,6-diphenylpyridazine (23) and 3-(2-chloroethyl)-2-phenylindole (22). 8b-Methoxy-, ethoxy-, and propoxy-1,2,3,3a,4,8b-hexahydro-3a-phenylcyclopent[b]indoles (27), (26), and (28), respectively, are isolated from the reaction of cyclobutyl phenyl ketone phenylhydrazone in cooled methanol, ethanol, and propan-1-ol, respectively, saturated with hydrogen chloride.