Stereospecific Synthesis of Quaternary Stereocenters from Tertiary Benzylic Carboxylates

Nickel-catalyzed, stereospecific cross-couplings via activation of secondary C-O bonds have been well developed in the past few years. Meanwhile, stereospecific cross-couplings of tertiary electrophiles have rarely been explored. Herein, we describe a nickel-catalyzed, ligand-free Suzuki-Miyaura vinylation, using easily prepared, highly enantioenriched tertiary benzylic carboxylates to install quaternary stereocenters in high yields and ee's. This method allows stereospecific vinylation of these substrates for the first time and is a rare example of stereospecific coupling that overcomes the requirement for a naphthyl group on the benzylic carboxylate.