Electrochemical Enol Ether/Olefin Cross-Metathesis in a Lithium Perchlorate/Nitromethane Electrolyte Solution

摘要

Transition-metal-catalyzed olefin cross-metathesis plays an important role in the construction of various carbogenic skeletons by allowing the exchange of substituents between different olefins via an activated key intermediate consisting of a four-membered ring coordinated to a transition metal. Alternatively, electrochemical reactions have proven to be a viable method in triggering reactions between different olefins by reversing the polarity of alkenes and initiating radical anion- (or cation-) based reactions. Electrochemically activated olefin cyclodimerization, for example, can effectively lead to the intermolecular formation of four-membered rings. Moreover, we reported an electrocatalytic intermolecular formal [2+2] cross-coupling of electron-rich olefins (Scheme 1). The anodic oxidation of enol ethers that bear a methoxyphenyl group can be used to trigger an intermolecular formal [2+2] cycloaddition with varied alkenes. In this case, the intermolecular olefin coupling was assisted by a unique lithium perchlorateitromethane electrolyte solution and the methoxyphenyl group of the substrates served as an intramolecular electron donor to form the cyclobutane ring. Herein, we describe novel electrochemical olefin cross-metatheses between anodically activated enol ethers and aliphatic alkenes.