Silver(I) versus Gold(I) Catalysisin Benzannulation Reaction: A Versatile Access to Acridines

Abstract

A silver/gold-catalysed benzannulation reaction is described. In the presence of catalytic amounts of gold and/or silver salts, the reaction of silyl enol ethers onto alkynes occurs under mild conditions to produce the corresponding polycyclic aromatic systems (acridine, quinoline or naphthalene cores) in good to high yields. Among the catalysts investigated, AgOTf has been chosen as a general catalyst for this reaction which likely proceeds through silver(I) activation of the alkynyl moiety leading to a subsequent cycloisomerisation reaction.