COMPARATIVE REACTIVITIES OF TRIMETHYLSILOXY GROUPS WITH THE HYDROZIRCONATION REAGENT, CP2ZR(H)CL

The trimethylsilylethers of unsaturated alcohols yield different compounds on reaction with Cp2Zr(H)Cl (1) depending on the length and branching of the alkenyl chain. With the hex-1-en-6-ol derivative the usual product of hydrozirconation is obtained in high yield. The reaction of the silylated 3-methyl-but-1-en-3-ol (11) is however, accompanied by hydrogenation of the SiO bond. The main products are trimethylsilane and the yellow complex Cp2Zr(Cl)CH2CH2C(CH3)2 OZr(Cl)Cp2 (12). The molar ratio of the reactants determines the final products of the reaction of allyl trimethylsilyl ethers 3 and 1. An equimolar preparation yields mainly the usual product of hydrozirconation, whereas an excess of 1 favours the formation of a binuclear five-membered chelate {A figure is presented} (5) and trimethylsilane. CO inserts readily into the ZrC bond of 12, but 5 does not react with CO. The binuclear structure of 12 was established by an X-ray diffraction study. The character of the ZrO and ZrC bonds is discussed in terms of these results. © 1990.