Hydrosilylation unsaturated hydrocarbons

The discussion of the activation of bonds containing a group 15 element is continued in chapter five. D.K. Wicht and D.S. Glueck discuss the addition of phosphines, R2P-H, phosphites, (R0)2P(=0)H, and phosphine oxides R2P(=0)H to unsaturated substrates. Although the addition of P-H bonds can be sometimes achieved directly, the transition metal-catalyzed reaction is usually faster and may proceed with a different stereochemistry. As in hydrosilylations, palladium and platinum complexes are frequently employed as catalyst precursors for P-H additions to unsaturated hydrocarbons, but (chiral) lanthanide complexes were used with great success for the (enantioselective) addition to heteropolar double bond systems, such as aldehydes and imines whereby pharmaceutically valuable a-hydroxy or a-amino phosphonates were obtained efficiently. 

The technique based on the bonding of hydridechlorosilanes with unsaturated hydrocarbons (hydrosilylation)... 

A convenient method for producing some silicone monomers is a reaction of bonding hydridechlorosilanes to unsaturated hydrocarbons. In recent years this method has been used in industry quite extensively. Its essence is in hydridechlorosilanes entering the reaction of hydrosilylation of unsaturated hydrocarbons in the presence of catalysts. 

Hydrosilylation of unsaturated hydrocarbons is the most essential procedure for creating Si-C bonds. It is an addition of Si-H units across ir-systems such as C=C double or C=C triple bonds and may occur on two different reaction modes. Radical hydrosilylation is initiated with ultraviolet (UV) hght, y-irradiation, or radical starters such as azobis(isobutyronitrile) (AIBN) or peroxides. However, there are some drawbacks which have to be taken into account, such as competition of... 

In reactions that are formally analogous to hydrosilylation, transition-metal complexes catalyze the insertion of unsaturated hydrocarbons into other Si-X (X = C, Si, Sn, etc.) bonds. Palladium catalysts seem to work best in many of these reactions. The work of Kumada and coworkers has already been referred to in connection with metal-catalyzed silylene transfer to alkynes (see equation 47)95"97. Sakurai s group has shown that the cyclic disilane 55 will add to alkynes in the presence of a palladium catalyst (equation 110, see also equation 80). The unstrained disilane Me3SiSiMe3 undergoes a similar reaction... 

Unsaturated hydrocarbons with a functional group are also active in the reaction of hydrosilylation. The hydrosilylation of haloalkenes, nitroalkenes, aminoalkenes, cyanoalkenes, alkenyl alcohols, phenols, aldehydes, acids, and... 

The addition of metal-hydrogen bonds across carbon-carbon multiple bonds, called hydrometallations, are very important, versatile transformations in organic synthesis. First, they allow the synthesis of new organometallic compounds. The products thus formed may be further transformed into other valuable compounds. The two most important reactions, hydroboration and hydrosilylation, will be treated here in detail, whereas other hydrometallation reactions (hydroalanation, hydro-zirconation) will be discussed only briefly. Hydrostannation, a very important transformation of substituted unsaturated compounds, has no significance in the chemistry of hydrocarbons possessing nonactivated multiple bonds. 

Allyl derivatives of hydrocarbons with functional group were often used as starting materials. The hydrosilylation of allylperfluoroethers with methyl(chloro)silanes is a frequently used method for synthesis (after hydrolysis and polycondensation) of fluorine-containing polymers (162). Unsaturated esters of unsaturated carboxylic acids in the reaction of hydrosilylation give silyl derivatives of carboxylic acid (e.g., 3-methacryloxypropyltriethoxysilane). 

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