Regiospecific synthesis of alpha-lithiated alkoxysilanes

alpha-Lithioalkoxysilanes, [(RO)R-2'Si]CH(Li)(R ") (R = Me, Et; R' = Me, Ph ; R " = H, SiMe3), can be prepared by treating the appropriate alkoxysilane with tert-butyllithium in hydrocarbon solvents. For R = Me or Et, R' = Me, and R " = H or SiMe3, the alpha-lithioalkoxysilanes are produced in high y ield. Similar treatment of alkoxysilane 12, EtOPh2SiCH3, afforded the corre sponding alpha-lithioalkoxysilane 13 (R = Et, R' = Ph and R " = H), in mode rate yield, along with substitution product 14, tert-BuPh2SiCH3. Analogous reactions with n-butyl- and sec-butyllithium in hydrocarbon solvent produce d significant or exclusive substitution at silicon, rather than alpha-lithi ation. (C) 2000 Elsevier Science S.A. All rights reserved.