Palladium/norbornene/copper-catalysed intermolecular thio-esterification from ketones: modular access towards tetrasubstituted vinyl sulfides

Abstract

Herein, we disclosed a strategy to access diverse tetrasubstituted vinyl sulfides from cyclic ketones via palladium/norbornene/copper catalysed dual functionalization of the corresponding enol triflates, allowing simultaneous installation of thio and alkoxycarbonyl groups at vicinal positions of 1,2-disubstiuted alkene in a regioselective fashion. A copper salt was proven to enhance the reactivity of the electrophile to achieve the desired selectivity without using commonly used C2 amide-substituted norbornene. Readily available thiocarbonates are suitable bifunctional electrophiles; various functional groups could be tolerated. The protocol is scalable and permits orthogonal coupling in the presence of other functionalization handles.