title: Intra- and intermolecular reactions of indoles with alkynes catalyzed by gold.
abstract: Indoles react intramolecularly with alkynes in the presence of gold catalysts to give from six- to eight-membered-ring annulated compounds. The cationic Au(I) complex [Au(P{C(6)H(4)(o-Ph)}(tBu)(2))(NCMe)]SbF(6) is the best catalyst for the formation of six- and seven-membered rings by 6-endo-dig, 6-exo-dig, and 7-exo-dig cyclizations. Indoloazocines are selectively obtained with AuCl(3) as catalyst in a rare 8-endo-dig process. In this process allenes or tetracyclic annulated derivatives are also formed as a result of an initial fragmentation reaction. The intermolecular reaction of indoles with alkynes proceeds to form 3-alkenylated intermediates that react with a second equivalent of indole to give bisindolyl derivatives. Indoles that are substituted at the 3-position react intermolecularly with alkynes to give 2-alkenylated intermediates that can be trapped intramolecularly with the appropriate nucleophiles.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Catalina
authors.initials: C
authors.lastname: Ferrer
authors.forename: Catelijne H M
authors.initials: CH
authors.lastname: Amijs
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Echavarren