In Situ Generation of Silylzinc by Si−B Bond Activation Enabling Silylzincation and Silaboration of Terminal Alkynes

A new protocol has been designed for the in situ generation of unstable Si−Zn species through the reaction of dialkylzinc, phosphine, and silylborane (Si−B). Successive reactions with various terminal alkynes using this protocol enabled highly controllable regio‐/stereo‐/chemoselective silylzincation and silaboration on demand without the need for a transition‐metal catalyst. On demand: The in situ generation of silylzinc species was achieved by reacting dialkylzinc, phosphine, and silylborane. DFT calculations indicated that Si−B bond cleavage would afford the Si−Zn species. By using this protocol, successive reaction with various terminal alkynes enabled highly controllable regio‐/stereo‐/chemoselective silylzincation and silaboration of terminal alkynes on demand, thus affording synthetically versatile and densely functionalized vinylsilane and vinylboron derivatives.