Copper-catalyzed, silver-mediated formal [3+2] cycloaddition of simple alkynes with β-ketoesters through propargylic C(sp3)-H functionalization.

A copper-catalyzed propargylic [3+2] cycloaddition of simple alkynes with β-ketoesters through the propargylic C(sp3)-H functionalization has been realized. Under catalysis by CuI in combination with 1,10-phenanthroline hydrate as the ligand and Ag2CO3 as a bifunctional reagent (oxidant and base), the reaction proceeds smoothly with a broad substrate scope, thus providing a variety of highly functionalized furans in moderate to high yields. This represents the first successful example of the catalytic propargylic cycloaddition of simple alkynes with bisnucleophiles based on the propargylic C(sp3)-H functionalization strategy.