A facile synthesis of 2-substituted indoles from (2-aminobenzyl)triphenylphosphonium salts

A variety of 2-substituted 1-acylindoles were obtained in yields ranging from 40 to 94% by intramolecular Wittig reaction employing (2-aminobenzyl)triphenylphosphonium derivatives and acid anhydride in the presence of triethylamine. The reaction of (2-aminobenzyl)phosphonium derivatives with various acyl chlorides in 2,6-lutidine also proceeded to give the corresponding indoles in 28–67% yields.