A novel synthesis of β-ketosilanes via organoboranes

A convenient, novel synthesis of β-ketosilanes based on (Z)-1-bromo-1-alkenylboronate esters is developed. α-Bromo-(Z)-1-alkenylboronate esters readily available using literature procedures smoothly undergo a reaction with trimethylsilylmethyllithium in tetrahydrofuran to provide the corresponding ‘ate’ complexes. These ‘ate’ complexes will undergo intramolecular nucleophilic substitution reactions to afford the corresponding (E)-trisubstituted olefins containing trimethylsilylmethyl moiety. The oxidation of these intermediates with sodium acetate and hydrogen peroxide provides β-ketosilanes in good yields (63–75% yield).