Synthesis of Fused 4,5-Disubstituted Indole Ring Systems by Intramolecular Friedel−Crafts Acylation of 4-Substituted Indoles

4-Substituted indoles containing a variety of electrophiles and N-substituents undergo Friedel-Crafts acylation to give exclusively the products of cyclization at the 5-position of indole. These indanones and tetralones have been scarcely prepared and are subunits in natural products and analogues of potential biological significance.