Regioselectivity-Switchable Catalytic Annulations of Alkynyl α-Diketones and α-Cyanoketones.

Regioselectivity-switchable reactions hold irreplaceable importance in the construction of diversified architectures. In this work, Brønsted base-catalyzed regioselectivity-switchable annulations between alkynyl α-diketones and α-cyanoketones have been achieved for the first time, delivering a series of skeletally thoroughly different dihydrofurofuran and furan derivatives. A range of novel transformations of the products can be realized.