Transition-metal-free synthesis of 1,1-diboronate esters with a fully substituted benzylic center via diborylation of lithiated carbamates.

A transition-metal-free lithiation-borylation method has been developed to access a variety of 1,1-diboronate esters with a fully substituted benzylic center from readily available secondary benzylic N,N-diisopropyl carbamates. The method is applicable to scale-up synthesis of 1,1-diboron compounds. Furthermore, the current method is also applicable to synthesizing optically active 1,1-silylboronate esters.