ZrCl4-Mediated Regio- and Chemoselective Friedel-Crafts Acylation of Indole

An efficient method for regio- and chemoselective Friedel-Crafts acylation of indole using acyl chlorides in the presence of ZrCl4 has been discovered. It minimizes/eliminates common competing reactions that occur due to high and multiatom-nucleophilic character of indole. In this method, a wide range of aroyl, heteroaroyl alkenoyl, and alkanoyl chlorides undergo smooth acylation with various indoles without NH protection and afford 3-acylindoles in good to high yields.