Rhodium(III)-Catalyzed Oxidative ortho-Olefination of Phenyl Carbamates with Alkenes: Elucidation of Acceleration Mechanisms by Using an Unsubstituted Cyclopentadienyl Ligand.

It has been established that an unsubstituted cyclopentadienyl (Cp) Rh(III) complex is an effective catalyst for the oxidative ortho-olefination of phenyl carbamates with both acrylates and styrenes under mild conditions. In addition, diolefination of a protected BINOL (1,1'-binaphthalene-2,2'-diol) proceeded in high yields and disubstituted acrylates could participate in this catalysis. Experimental and theoretical mechanistic studies elucidated that an electron-deficient nature of the unsubstituted CpRh(III) complex accelerates both the electrophilic aryl C-H rhodation and the rate-limiting alkene insertion steps.