Abstract Indolyl enol ethers, generated from the alkoxy (indolyl) carbenium tetrafluoroborates 1 by treatment with sodium hydride, can be trapped with dimethyl acetylenedicarboxylate or N-phenylmaleimide to furnish the selectively functionalized carbazoles 3, 4, 5, 9, 10, and 13. In addition, the biaryl derivatives 6 and 11 are produced by a ring-opening reaction of the primarily formed Diels-Alder adduct. In the case of the biaryl ...
