Metal-Free, Stereospecific Bis-Silylation of Functionalized Alkynes with NHC-Supported Silylaminosilylene

The NHC-supported silylaminosilylene Ar­(SiMe3)­N­(Cl)­Si­(IiPr) (1; Ar = 2,6-iPr2C6H3, IiPr = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) is an efficient and stereospecific bis-silylation reagent for a range of functionalized alkynes to yield cis-1,2-bis-silylated alkenes via a 1,4-silyl migration from the amino nitrogen atom to an alkyne carbon atom. The reaction is regio- and stereospecific for terminal alkynes with an electron-withdrawing substituent, thus providing a facile access to 1,2-bis-silylated alkenes with two different silyl groups.