Fluorosilanes synthesis

This common way of synthesis has to cope with the problem that the reaction is nearly uncontrollable because of polycondensation [1], Intermediates, e.g., chlorosilanols, cannot be proved or isolated. However, starting with the alkaline hydrolysis of fluorosilanes, halosilanols, silandiols, and aminosilanols can be prepared and stabilized by bulky groups. 

Cyclodisilazane anions and cyclodisilazanes in cw-conformation are found in the reaction of dilithiated bis(silylamino)fluorosilanes with chlorotrimethylsilane. The dilithium salt of the corresponding bis(silylamino)chlorosilane is obtained. LiCl elimination in the presence of THF leads to the formation of silaamidides (which are isolated as dimers),19,26 four-membered cyclodisilazane anions and (thf)3Li-Cl-Li(thf)36 or Li(thf)/ cations (Scheme 10).19,27 Hydrolysis of dimeric silaamidides is a facile synthesis leading to cyclodisilazanes in the cw-conformation. Examples are shown in Figs. 1 and 2 (Scheme 11).19,27... 

The synthesis of array L7 is reported in Fig. 8.22. Compound 8.38 was reacted simultaneously with amines (Mi, two representatives), aldehydes (Mi, five representatives), and isonitriles (Ms, two representatives) to give 10 compounds (not all the combinations were reacted). The reaction was performed in trifluoroethanol (TFE), another hybrid fluorous-organic solvent (step a. Fig. 8.22), and after evaporation of the TFE, the crude product 8.39 was purified by two-phase extraction between fluorous solvents and benzene (step b). After evaporation of the solvent, the fluorous tag was cleaved with TBAF (step c) and a triphasic extraction (step d, Eig. 8.22) was performed to remove the fluorosilane tag and acid 8.38-related impurities extracted into the fluorous layer. Excess TBAE and TBAE-related impurities partitioned into the acidic aqueous layer. Yields and purities of the synthetic protocol are reported together with the structures of the library members L7a-j in Table 8.2. 

Base-catalyzed redistributions are also efficient and have been used successfully in the synthesis of fluorosilanes. The high volatility of fluorosilanes allows the easy separation of products. 

An established pathway to naphthylsilanes is the Grignard reaction which, in this case, requires fluorosilanes as silicon components, as can be shown by the synthesis of bis (l-naphthyl)difluorosilane (234) (equation 113a)131. However, for the synthesis of tetrakis (2-naphthyl)silane (235) it is preferable to use lithiated naphthalene (equation 113b)142. In... 

The stepwise synthesis of Si-0 ehains and rings is feasible from alkali metal silanolates and fluorosilanes. The first heptasiloxane was prepared in this way (Eq. 

Schulte, M. Schiirmann, M. Jurkschat, K. [cyclo-CH2 Sn(Cl2)CH2Si(Me2) 20] Synthesis and complexa-tion behavior of a novel, cyclic, bidentate Lewis acid and its conversion into a tin-containing fluorosilane with intermolecular Si-F- Sn bridges. Chern. Fur. J. 2001. 7. 347-355. 

In contrast to carbon chemistry, in silicon chemistry diols and silanol halides can be stabilized by bulky groups. Stepwise synthesis of cyclic and acyclic siloxanes is possible with fluorosilanes and alkaline derivatives (Scheme 1). 

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