Transition-Metal-Free Alkynylation of 2-Oxindoles through Radical-Radical Coupling.

An effective transition-metal-free approach for the synthesis of 3-alkynyl-2-oxindoles through a radical-radical coupling process was developed. The reaction was general with respect to 2-oxindoles and iodoalkynes and provided the desired products bearing a quaternary center at C3 in good to excellent yields, making this method synthetically viable and attractive for the synthesis of spiro and fused 2-oxindole derivatives.