Iridium-Catalyzed Regioselective C(sp3)-H Silylation of 4-Alkylpyridines at the Benzylic Position with Hydrosilanes Leading to 4-(1-Silylalkyl)pyridines

The regioselective silylation of C(sp(3))-H bonds at the benzylic position in 4-alkylpyridines with hydrosilanes is described. The reaction proceeds in the presence of a catalytic amount of Ir-4(CO)(12) or Ir(acac)(CO)(2), which possess CO as a ligand, or [Ir(OMe)(cod)](2) under 1 atm of CO. After optimizing the reaction conditions, by using other pyridine derivatives, such as 3,5-dimethylpyridine, as additives, the low product yields of 2-substituted 4-methylpyridines were improved markedly.