Taming Gold(I)-Counterion Interplay in the De-aromatization of Indoles with Allenamides

A careful interplay between the p electrophilicity of a cationic Au-I center and the basicity of the corresponding counterion allowed for the chemo-and regioselective inter- as well as intramolecular de-aromatization of 2,3-disubstituted indoles with allenamides. The silver-free bifunctional Lewis acid/Bronsted base complex [{2,4-(tBu)(2)C6H3O}(3)PAuTFA] assisted the formation of a range of densely functionalized indolenines under mild conditions.