Organosilanes addition reactions

Stereochemistry of Chiral Organosilane Addition Reactions. The addition reaction of optically active organosilicon hydrides to oct-1-ene has been reported to proceed with retention of configuration at silicon in the presence of platinum catalysts (199) (Scheme 46). The predominant stereochemistry and stereoselectivities were determined by a chemical correlation using pathways of known stereochemistry. 

Given the above possible reaction mechanism, it is then intriguing to speculate that another approach to the same stereoselective reduction of a vinyl sulphone could be achieved by the use of a suitably sterically hindered organosilane, as outlined in equation (64). Such a reaction would provide an interesting test for the stereoelectronics of a conjugate addition reaction by a second-row heteroatom to a vinyl sulphone. 

Vinylsilanes are proper compounds which have won great appreciation as facile intermediates for many sorts of application. They are prepared either by addition reactions of acetylenes (vide supra) or by elimination reactions of saturated organosilanes. The main reactions, carried out with vinylsilanes, are addition reactions to obtain saturated organosilanes or electrophilic substitutions of the silyl group under Friedel-Crafts conditions where a rapid cleavage of the silyl moiety occurs (Scheme 8). 

Addition reactions of hydrosilanes to alkenes shown in the following general scheme are one of the most frequently utilized reactions for the preparation of organosilanes (equation 20). ... 

Transition metals have already established a prominent role in synthetic silicon chemistry [1 - 5]. This is well illustrated by the Direct Process, which is a copper-mediated combination of elemental silicon and methyl chloride to produce methylchlorosilanes, and primarily dimethyldichlorosilane. This process is practiced on a large, worldwide scale, and is the basis for the silicones industry [6]. Other transition metal-catalyzed reactions that have proven to be synthetically usefiil include hydrosilation [7], silane alcdiolysis [8], and additions of Si-Si bonds to alkenes [9]. However, transition metal catalysis still holds considerable promise for enabling the production of new silicon-based compounds and materials. For example, transition metal-based catalysts may promote the direct conversion of elemental silicon to organosilanes via reactions with organic compounds such as ethers. In addition, they may play a strong role in the future... 

The derivatization method is compensated by the electrophihc addition reaction using organosilicon reagents [40-43]. Thus, the squaric acid family of derivatives, e.g., dichloride 17, methyl ester chloride 18, amide chloride 19, and diester 5 are the partners of the reactions with allylsilanes, silyl enol ethers, and silyl ketene acetals (Scheme 3). In this case, 1,2- and 1,4-addition to 20 and 21, respectively, are regulated by the substitution pattern of unsaturated organosilanes, kind of Lewis acid catalysts, and the reactivity of acid derivatives. The less congested is the reaction site, the more preferable is 1,2-... 

Finally, organosilane reagents have also been used. Oi and coworkers in 2002 developed a novel, additive-free, and clean conjugate addition reaction of organosUoxanes to a,(3-unsaturated carbonyl... 

At low temperatures perfluoro-w-propyllithium, prepared in the above manner, underwent displacement and addition reactions common to alkyl-lithium compounds. The experimental technique (7) involved addii methyllithium and the reactant dissolved in ether to heptafluoro- -propyl iodide in the same solvent. In this manner, certain aldehydes and ketones afforded the expected alcohols, and diethyldichlorosilane gave a mixture of the organosilanes n-C3F7(C2H5)2SiCl and ( -C3F7)2Si(C2H5)2. 

Addition to Olefins. OrganohydrosHanes can also be prepared by addition of halosHanes and organosilanes containing multiple Si—H bonds to olefins. These reactions are catalyzed by platinum, platinum salts, peroxides, ultraviolet light, or ionizing radiation. 

The partially alkoxylated chlorotitanates, (RO) TiCl, can be prepared in high purity by reaction of TiCl with an organosilane ester, Si(OR)4 (see Silicon compounds). The degree of esterification of the titanium can be controlled by the amount of silane ester used. When is 3 or 4, the addition of the appropriate alcohol and an amine receptor is required (5). 

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