A novel route to pentacoordinated organylsilanes and -germanes

New convenient methods of sila- and germatranes synthesis from ethoxy- and tetraorganylsilanes and -germanes have been elaborated. The reaction of ethoxysilanes with boratrane in the presence of catalytic amounts of metal alcoholates has been investigated. Dimethylformamide (DMF) as a solvent and NaOEt as a catalyst used instead of xylene and Al(O^i-Pr)₃ were found to give better yields. The possibility of using alkoxy-, aminosilanes, tetraethoxygermane and even tetraorganylsilanes in this reaction leading to the corresponding atranes with good yields has been demonstrated. Triethanolamine in the presence of catalytic amounts of base or CsF easily substitutes furyl-, dihydrofuryl-, dihydropyranyl- and thienyl groups in tris- and tetraheterylsilanes, leading to organylsilatranes with good to excellent yields.