Gold-Catalyzed Cascade Reactions of Alkynes for Construction of Polycyclic Compounds

The development of cascade reactions is an area of considerable interest in modern organic chemistry. Efficient cascade reactions realize the economical synthesis of complex target molecules through multiple bond formations in a single operation. Elementary reactions that form fewer waste products are desirable in terms of atom economy and in order to suppress side product formation in sequential processes. Recent advances in homogeneous gold catalysis have opened up further possibilities for cascade reactions. In this review, recent advances in gold-catalyzed cascade cyclizations of alkynes are summarized. In particular, cascade reactions based on nucleophilic/electrophilic addition, carbene cyclopropanation/insertion, ring expansion, and cycloaddition are highlighted. Notably, many of the cascade reactions shown in this mini-review feature no theoretical waste products.