883149-29-9Relevant academic research and scientific papers
Intra- and intermolecular reactions of indoles with alkynes catalyzed by gold
Ferrer, Catalina,Amijs, Catelijne H. M.,Echavarren, Antonio M.
, p. 1358 - 1373 (2007)
Indoles react intramolecularly with alkynes in the presence of gold catalysts to give from six- to eight-membered-ring annulated compounds. The cationic AuI complex [Au(P{C6H4-(o-Ph))(tBu) 2)(NCMe)]SbF6 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 AuCl3 as catalyst in a rare 8-endodig process. In this process alienes 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.
