Synthesis of Silylated Alkylboronic Acids and Esters via Hydroboration of Allylic and Vinylic Trimethylsilanes

Representative allylic trimethylsilanes and isopropenyltrimethylsilane were hydroborated with dichloroborane, and the products were transformed into the corresponding β-or γ-trimethylsilylboronates. Synthesis of 2-trimethylsilylethylboronic acid and its diethyl ester via hydroboration of trimethylvinylsilane with diisopinocampheylborane, followed by liberation of a-pinene is described.