Synthesis of various boron-containing disilanes

The stepwise reaction of the Si-Cl functions of 1,1,2,2-tetrachlorodimethyldisilane with RMgBr using the diethylamino unit as protecting group enables the synthesis of disilanes Si₂Me₂R_xCl_4–x, bearing one to four olefinic substituents (R = vinyl, -allyl and ethynyl). The catalyst free hydroboration of such molecules represents a convenient way to prepare boron containing chlorodisilanes. 9-BBN exhibits a very high regioselectivity in the hydroboration of vinyl-, allyl-or ethynyldisilanes. In case of the ethynyl group, the hydroboration of 1,1,2-trichloro-2-ethynyldimethyldisilane and 1,2-dichloro-1,2-diethynyldimethyldisilane by the twofold addition of the 9-BBN in two separate steps was confirmed by NMR spectroscopy.