Organometallic Syntheses of Carbosilanes

In the investigations into the organometallic synthesis of carbosilanes, several different objectives were pursued  

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The investigations carried out on the organometallic synthesis of carbosilanes and presented in this paper indicate the progress achieved in this field in the years between 1967 and 1971 in cooperation with Dr. P. Schober, Dr. M. Hahnke and Dr. G. Maas. The yields of these syntheses are not all satisfactory yet, in most cases with the cyclization reaction. There is no doubt that the procedures described can be extended and simplified. However, it is also apparent that only some of the compounds (and their derivatives) which arise from the pyrolysis of the methylchlorosilanes and of tetramethylsilane can be obtained by organometallic synthesis38. The development of this field of chemistry requires extensive advances in methods for synthesis. 

The organometallic syntheses of cyclic and polycyclic carbosilanes have already been summarized [60]. These syntheses are made possible partly by initial incorporation of a shielding group which will be transferred into a functional group before the last reaction stage. Especially suitable in such circumstances are Si—Ph groups, which are easily cleaved ... 

The synthetic routes known to date to form carbosilanes are based on the gas phase pyrolysis of methylsilanes, on the reaction of CH2CI2 and CHCI3 with silicon (Cu-catalysed), on the reaction of Si-methylated carbosilanes with AlBr3 or AICI3, and on organometallic syntheses. 

From the results on the effect of AlBr3 on carbosilanes presented here, it is recognized that these reactions show potential for development. After synthesis of suitable starting materials, a further insight could be gained into the several reaction pathways. This is often a toilsome undertaking, but it should not be overlooked that only in this way can an increased number of compound types be identified, substances that cannot be revealed under present circumstances by ordinary organometallic syntheses. 

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