ALLYL SILANES IN THE SYNTHESIS OF FUNCTIO NAL SILYL TRIFLATES

The highly reactive silyl triflates are valuable reagents in organosil icon chemistry. New difunctional silyl triflates, R2SiX(OTf) (X = CH2= CHCH2, CH2=CH, OCH3; OTf = OSO2CF3) have been prepared by substitution of allyl or phenyl groups at silicon by the trifluormethanesulfonyl g roup. The presence of the electron-withdrawing triflate group leads to a strong deactivation of the other substituents at the silicon atom, and therefore the displacement of a second group is much slower than t he first step. For this reason a stepwise substitution on the silicon atom has been found. The reaction rate of the cleavage of the Si-Y bon d decreases in the order (Y =) CH2=CHCH2 > C6H5 > CH2=CH, CH=C, OCH3 > CH3.