Synthesis of 3-Allenylindoles and 3-Dienylindoles by Bronsted Acid Catalyzed Allenylation of 2-Arylindoles with Tertiary Propargylic Alcohols

The Bronsted acid catalyzed direct nucleophilic substitution of tertiary propargylic alcohols with 2-aryl-substituted indoles has been studied. A competitive allenylation process takes place with appropriate substituents on the alkynol moiety. Starting from 2-arylindoles, new 3-allenyl and 3-dienylindole derivatives have been easily synthesized.