Oxyacylation of Iodoalkynes: Gold(I)-Catalyzed Expeditious Access to Benzofurans.

(Acetonitrile)[1,3-bis(2,6-diisopropylphenyl)-imidazole-2-ylidene] gold(I) catalyzes the cycloisomerization of 2-(iodoethynyl)aryl esters to give 3-iodo-2-acyl benzofurans. This catalytic transformation is the result of an unprecedented selective synthetic event, which comprises a [1,2]-iodine shift, a C-O ring-closure step, and a C-C bond-formation that installs the ketone functionality into the new ring. Experimental evidence supports the involvement of a β-iodo-substituted gold vinylidene as the intermediate species. The reaction tolerates different substitution patterns at the phenol moiety and a wide diversity of groups at the carboxylic fragment, including not only alkyl but also alkenyl, aryl, and heteroaryl groups.