Transition-Metal-Free Defluorosilylation of Fluoroalkenes with Silylboronates

Silylated fluoroalkenes are important synthetic intermediates with complementary reactivity, which play a key role in the construction of natural products, pharmaceuticals, and manmade materials. Converting the normally highly stable fluoroalkenes into silylated fluoroalkenes by selective defluorosilylation is a challenging task. Herein, we report a simple, inexpensive and robust defluorosilylation of a variety of fluoroalkenes with silylboronates in the presence of alkoxy base to directly synthesize various silylated fluoroalkenes. The protocol features mild and safe reaction conditions that avoid a catalyst, a transition metal, a ligand, and high reaction temperature and tolerates a wide scope of fluoroalkene substrates without compromising the efficiency. Density functional theory calculations show that transient silyl anion complex undergoes an S(N)2' or S-N(V) substitution, which is responsible for this base-mediated defluorosilylation.