Gold-catalyzed intermolecular formal (3+2) cycloaddition of stabilized vinyldiazo derivatives and electronically unbiased allenes.

The reaction of electronically unbiased allenes with alkenyldiazo compounds in the presence of gold catalysts provided alkylidenecyclopentene derivatives resulting from a formal intermolecular (3+2) carbocyclization. A stepwise mechanism involving initial activation of the diazo component and subsequent formation of an allyl cation intermediate has been proposed. This process represents the first intermolecular gold-catalyzed cycloaddition involving non-activated allenes.