Regioselective Copper-Mediated Synthesis of Thieno[2,3-c]pyrane-7-one, Indolo[2,3-c]pyrane-1-one, and Indolo[3,2-c]pyrane-1-one

In the presence of copper(I) iodide, heteroaromatic beta-iodo-alpha,beta-unsaturated carboxylic acid systems opposed to terminal alkyne afford selectively 6-endo-dig cyclization products via a tandem coupling oxacyclization reaction.