Organosilicon compounds reactions

Organosilicon compounds are widely used in our daily life as oil, grease, rubbers, cosmetics, medicinal chemicals, etc. However, these compounds are not naturally occurring substances but artificially produced ones (for reviews of organosilicon chemistry, see [59-64]). Hydrosilylation reactions catalyzed by a transition-metal catalyst are one of the most powerful tools for the synthesis of organosilicon compounds. Reaction of an unsaturated C-C bond such as alkynes or alkenes with hydrosilane affords a vinyl- or alkylsilane, respectively (Scheme 16). 

Activation parameters of the organosilicon compounds reactions with OH groups on the pyrogenic silica surface (A, pre-exponential factor and observed activation energy on free surface) [79-81], the estimated heat of adsorption complex formation (Qads) and activation energy of proton transfer (E j ) from [49]... 

Photofragmentations of Organosilicon Compounds. - Reactions of carbon tetrachloride with dimethylsilylene (Me2Si ), generated by photolysis of the ben-zo-7-silanorbornadiene (42), have been investigated by means of laser pulse... 

Some organosilicon compounds undergo transmetallation. The allylic cyanide 461 was prepared by the reaction of an allylic carbonate with trimethylsi-lyl cyanide[298]. The oriho esters and acetals of the o. d-unsaturated carbonyl compounds 462 undergo cyanation with trimefhylsilyl cyanide[95]. 

Reactions of cyclic acetals with organosilicon compounds 97MI42. 

Hiyama, T. Organosilicon Compounds in Cross-Coupling Reactions. In Metal Catalyzed Cross-Coupling Reactions, Diederich, F., Stang, P. J., Eds. Wiley-VCH Weinhein, 1998 Chapter 10. 

In this section, the reactivities of organosilicon compounds for the Friedel-Crafts alkylation of aromatic compounds in the presence of aluminum chloride catalyst and the mechanism of the alkylation reactions will be discus.sed, along with the orientation and isomer distribution in the products and associated problems such as the decomposition of chloroalkylsilanes to chlorosilanes.. Side reactions such as transalkylation and reorientation of alkylated products will also be mentioned, and the insertion reaction of allylsilylation and other related reactions will be explained. 

To prepare multifunctionalized symmetric organosilicon compounds by the polyalkylation of benzene. (2-chloroethyi)trichlorosilane and (3-chloropropyl)tri-chlorosilane were reacted with benzene. Polyalkylations of benzene with (2-chloroethyl)silane and (3-chloropropyl)silane were carried out in the presence of aluminum chloride catalyst at a reaction temperature of 80 C. The reaction of benzene with excess (2-chloroethyI )trichlorosilanes afforded pcralkylated product, hexakis(2-(trichlorosilyl)ethyl)benzene in good yield (70%). ... 

General Features of Carbon-Carbon Bond-Forming Reactions of Organosilicon Compounds... 

Yoshida, J. Electrochemical Reactions of Organosilicon Compounds. 170, 39-82 (1994). Yoshihara, K. Chemical Nuclear Probes Using Photon Intensity Ratios. 157, 1-34 (1990). Yoshihara, K. Recent Studies on the Nuclear Chemistry of Technetium. 176, 1-16 (1996). Yoshihara, K. Technetium in the Environment. 176, 17-36 (1996). 

Since the silanone intermediates have been postulated as key intermediates in reports on the synthesis and reactions of organosilicon compounds,27 the isolation of a stable silanone and its characterization should be one of the most fascinating subjects in the future chemistry of low-coordinate organosilicon compounds. 

The application of bases other than fluoride for activation of organosilicon compounds to crosscoupling is documented. NaOH can replace fluoride in the cross-coupling of aryl and alkenyldichloroalkylsilanes with aryl halides, including chlorides. Apart from providing milder reaction conditions, the reaction in the presence of NaOH is applicable to a wider range of substrates ((85) and (86)).294... 

So far only a few examples of the uses of organosilicon compounds in cross-couplings have been published. Noteworthy is the smooth reaction with a sterically hindered substrate (87).295 The synthesis of the alkaloid nitidine included a cross-coupling step using an alkenylsilane (88),296 while the syntheses of some antitumor agents involved the alkenylation of unprotected iodouracyls using alkenyl-silicon species.297... 

Several methods, similar to those used to produce organosilicon compounds, are available for the preparation of germanium organyls. Organogermanium halides, which are the source of practically all other types of germanium organyls, can be formed by the direct reaction of aryl and alkyl halides with Ge/Cu alloys (equation 1). 

Scheme 5. Reactions of silicon tetrachloride and organosilicon compounds with stable nucleophilic carbenes.

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