Aerobic copper-catalyzed oxidative [6C+1C] annulation: an efficient route to seven-membered carbocycles

Abstract

It has been revealed for the first time that co-promoted by CuCl and NaH in the presence of molecular oxygen (air), the reaction of dicinnamoyl ketene dithioacetals as the acyclic C₆ synthons with ethyl cyanoacetate gives functionalized seven-membered carbocycles. A mechanism is proposed involving a tandem Michael addition–intramolecular radical cyclization–benzyl C(sp³)–H bond oxidation.