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

It has been revealed for the first time that co-promoted by CuCI and NaH in the presence of molecular oxygen (air), the reaction of dicinnamoyl ketene dithioacetals as the acyclic C-6 synthons with ethyl cyanoacetate gives functionalized seven-membered carbocycles. A mechanism is proposed involving a tandem Michael addition-intramolecular radical cyclization-benzyl C(sp(3))-H bond oxidation.