Palladium-Catalyzed Reaction of <i>o</i>-Alkynyltrifluoroacetanilides with 1-Bromoalkynes. An Approach to 2-Substituted 3-Alkynylindoles and 2-Substituted 3-Acylindoles

Abstract

The palladium-catalyzed reaction of o-alkynyltrifluoroacetanilides with 1-bromoalkynes affords free N-H 2-substituted 3-alkynylindoles in satisfactory to high yield. 2-Substituted 3-alkynylindoles revealed useful intermediates for the regioselective synthesis of 2-substituted 3-acylindoles. The latter can be prepared from o-alkynyltrifluoroacetanilides and 1-bromoalkynes via a one-pot cyclization-hydration protocol, omitting the isolation of 2-substituted 3-alkynylindoles.