Fully Substituted Conjugate Benzofuran Core: Multiyne Cascade Coupling and Oxidation of Cyclopropenone.

An unprecedented C═C double bond cleavage of cyclopropenone and dioxygen activation by multiyne cascade coupling has been developed. This chemistry provides a novel, simple, and efficient approach to synthesize fully substituted conjugate benzofuran derivatives from simple substrates under mild conditions. The density functional theory (DFT) calculations reveal that the unique homolytic cleavages of cyclopropenone and molecular oxygen are crucial to the success of this reaction.