Palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids: Construction of carbonyl-containing indolo[2,1-a]isoquinoline derivatives

A novel palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids is described, which provides a facile approach to access indolo[2,1-a]isoquinoline scaffolds. This method employs benzene-1,3,5-triyl triformate (TFBen) as the CO surrogate for the incorporation of a carbonyl group into indolo[2,1-a]isoquinoline scaffolds, and a variety of carbonyl-containing indolo[2,1-a]isoquinoline derivatives are prepared in good yields.