Synthesis of N-fused tricyclic indoles by a tandem [1,2] stevens-type rearrangement/1,2-alkyl migration of metal-containing ammonium ylides
(Chemical Equation Presented) An alkyne moiety is activated efficiently with a [W(CO)6] or [ReBr(CO)5] catalyst in the presence of an amine functionality in the title reaction of N-(2-alkynylphenyl)-amines. The resulting ammonium ylides undergo rearrangement to form a variety of N-fused polycyclic indole derivatives (see scheme; n = 1,2; R = alkyl, Ph).