Electrochemical Dearomatizing Spirocyclization of Alkynes with Dimethyl 2-Benzylmalonates to Spiro[4.5]deca-trienones

An electrochemical dearomatizing spirocyclization of alkynes with dimethyl 2-benzylmalonates for the preparation of spiro[4.5]deca-trienones has been developed. This approach adopts ferrocene (Cp2Fe) as an electrocatalyst to produce carbon-centered radical intermediates from C–H-based malonates, which obviates the forthputting of noble-metal reagents, sacrificial chemical oxidants and 2-bromomalonates. A wide variety of spiro compounds are efficiently prepared with satisfactory results under mild conditions.