Tunable Pd-Catalyzed Cyclizalion of Indole-2-carboxylic Acid Allenamides: Carboamination vs Microwave-Assisted Hydroamination

A variety or 3-vinyl-subtituted imidazo[1.5-a]indole derivatives were synthesized by intramolecular Pd-catalyzed cyclization oh the title allenamides through either a domino carbopalladation/exo-cyclization process or a novel hydroamination reaction that proceeds smoothly under microwave irradiation Both the observed pathways involve a pi-allyl-palladmin(II) complex arising from insertion of the allelic group into it palladium(II) species. the latter being formed In situ by the intervention of an aryl iodide or of the N-H group In both cases the role of nucleophile is covered by the Indole nitrogen