Asymmetric cyanoesterification of vinylarenes by electrochemical copper catalysis.

Abstract

The heterodifunctionalization of alkenes is an efficient and straightforward method for the preparation of highly functionalized molecules. However, enantioselective introduction of two different carbon-based functional groups in a single step using readily accessible and inexpensive starting materials presents a significant challenge. Herein, we report an electrochemical copper-catalyzed protocol for the asymmetric cyanoesterification of vinylarenes using commercially available alkyl carbazates and trimethylsilyl cyanide (TMSCN) as the sources of ester and cyano groups, respectively. The desired products could be obtained with good yields and enantioselectivities under mild conditions without the need for stoichiometric oxidants, providing sustainable access to versatile synthetic intermediates that could be smoothly converted into a variety of useful chiral building blocks. Mechanistic data are consistent with electrochemical copper-catalyzed generation of alkoxycarbonyl radicals from alkyl carbazates and the copper catalyst is also responsible for the stereoselective C-CN bond formation. The potential synthetic utility of this new electrocatalytic protocol is demonstrated in the concise synthesis of pharmacologically active molecules.