New Si-C bond forming reactions over solid-base catalysts

The reactions of silanes with carbanions generated on the surface of solid bases bring about the nucleophilic substitution at the Si atom to form Si-C bonds. The reaction of alkynes with silanes afforded alkynylsilanes. For example, the reaction of tert-BuC equivalent to CH or n-BuC equivalent to CH with Et2SiH2 in the presence of KNH2/Al2O3 gave tert-BuC-CSiEt2H and n-BuC equivalent to CSiEt2H in a 77% and 67% yield, respectively, at 329 K. Toluene also reacted with Et2SiH2 at 329 K to yield benzyldiethylsilane in a 85% yield. The reactions of l-alkynes with Me3SiC equivalent to CH in the presence of KNH2/Al2O3 or KF/Al2O3 resulted in a novel type of metathesis reaction between the two alkynes. For example, the reaction of PhC equivalent to CH with Me3SiC equivalent to CH afforded PhC equivalent to CSiMe3 and HC-CH in a high yield. These new types of base-catalyzed reactions provide new synthetic routes for Si-C bond formation. (C) 1998 Elsevier Science B.V. All rights reserved.