Reactivity of an NHC-stabilized silylene towards ketones. Formation of silicon bis-enolates vs. bis-silylation of the CO bond

Abstract

The NHC-stabilized silylaminosilylene Ar(SiMe₃)N(Cl)Si(IiPr) (1, Ar = 2,6-iPr₂C₆H₃, IiPr = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) reacted rapidly with a series of enolizable ketones under ambient conditions in a stereo- and regioselective fashion to afford silicon bis-enolates (2a–o) in high yields with the elimination of imidazolium salt. In contrast, reaction of 1 with two equivalents of benzophenone led to a slow bis-silylation of the CO double bond. All of the products have been characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy and HR-MS analysis. The configurations of compounds 2h–n were determined by NOESY experiments.