Cu(I)-Catalyzed [4 + 1] Cycloaddition of o-Quinone Methides with Terminal Alkynes: A Rapid Synthesis of 2,3-Disubstituted Benzofurans

A Cu(I)-catalyzed [4 + 1] cycloaddition reaction between o-quinone methides and terminal alkynes has been developed, demonstrating good compatibility with both stable and in situ generated o-quinone methides. This methodology offers several significant advantages, including operational simplicity, wide substrate compatibility, and the ability to access synthetically useful 2,3-disubstituted benzofuran compounds in generally good to high yields (44 examples, up to 91% yield).