Copper-Catalyzed Directed Hydroindolation/Annulation Sequence of Alkynes with Indoles via Copper Carbenes

Abstract

Described herein is an efficient copper-catalyzed tandem alkyne indolylcupration-initiated 1,2-indole migration/6πelectrocyclic reaction of allene-ynamides with indoles by the in situ-generated metal carbenes. This method allows the efficient synthesis of valuable indole-fused spirobenzo[f ]indole-cyclohexanes with high regio-and stereoselectivity. In addition, this reaction affords rapid access to the functionalized spirobenzo[f ]indole-cyclohexanes in the absence of indoles by a presumable 5-exo-dig cyclization/Friedel−Crafts alkylation via copper-containing all-carbon 1,4-dipoles.