β,β-Disubstituted C- and N-Vinylindoles from One-Step Condensations of Aldehydes and Indole Derivatives

Direct preparation of beta,beta-disubstituted C- and N-vinylindoles from condensation of aldehydes on indole derivatives is presented. Heating 1-methyl- and 1-benzylindole 3a,b with alkyl and aryl alpha-branched aldehydes and TFA in acetonitrile using microwave irradiation furnished 3-vinylindoles 1a-e in 18-76% yields. Under similar conditions, 3-substituted indoles 4a-c provided N-vinylindoles 2a-h in 16-98% yields.