Rhodium-Catalyzed Cyclization Reactions of γ-Alkynyl Aldehydes with Carboxylic Acid Anhydrides

It has been established that a cationic rhodium(I)/H-8-binap or binap complex catalyzes two different modes of cyclization of -alkynyl aldehydes with carboxylic acid anhydrides to give cyclic aldehyde gem-dicarboxylates and cyclic alkenyl esters through cleavage of the carboxylic acid anhydride C-O bond. The reaction of a terminal -alkynyl aldehyde with diethyl pyrocarbonate afforded a cyclic allylic carbonate with a high ee value.