Grignard reagents, reaction with silanes

These higher chlorides of silicon hydrolyze in the same way as does the tetrachloride, and they likewise undergo similar reactions with Grignard reagents and with sodium alkyls or aryls.30 Under some conditions, however, the silicon-silicon bond is cleaved by sodium.31 The silicon-silicon chains are destroyed by the action of aqueous alkalies, liberating hydrogen at the rate of one molecule of H2 per silicon-silicon bond, just as are the higher silanes. 

Allylic silanes are synthetically useful compounds that are usually prepared by reaction of chlorotri-alkylsilanes and allylic Grignard reagents, as with the preparation of the tcrt-butyldimethylsilane 744.620... 

Cleavage of Si—C bonds (12,243-245). This oxidation can be used to convert vinylsilanes in three steps to syn- or anti-1,2-diols. Thus Grignard reagents cleave epoxides of vinylsilanes selectively to (3-hydroxy silanes, which can be oxidized with retention of configuration to 1,2-diols. When applied to an (E)-vinylsilane, the sequence results in the syn-l,2-diol the an -l,2-diol is obtained from a (Z)-vinylsilane by the same reactions. 

TrimcthylsUylmcthylmagncsiiun chloride, (CH3)3SiCH2MgCl (1). Mol. wt. 146.99. The Grignard reagent is prepared in the usual way by reaction of magnesium with chloromethyl(trimethyl)silane.1... 

Trimethyl silane does not react under these conditions. However, under similar conditions, heptamethylcyclotetrasiloxane reacts with isoprene by 1,2-addition (78). Thiophene reacts with isoprene in the presence of phosphoric acid to give mainly 2-(3-methyl-2-butenyl)thiophene and some higher boiling compounds (79). Reactions of isoprene with Grignard reagents have been described (80,81). 

Next, reaction with a silicon-substituted Grignard reagent in the presence of Ni(II) gives an allyl silane. What kind of reaction is this, what was the role of phosphorus, and why was a metal other than sodium added (You know nothing specific about Ni as yet but you should see the comparison with another metal. Consult Chapter 23 if you need help.)... 

The acid or base elimination of a diastereoisomerically pure p-hydroxysilane, 1, (the Peterson olefination reaction4) provides one of the very best methods for the stereoselective formation of alkenes. Either the E- or Z-isomer may be prepared with excellent geometric selectivity from a single precursor (Scheme 1). The widespread use of the Peterson olefination reaction in synthesis has been limited, however, by the fact that there are few experimentally simple methods available for the formation of diastereoisomerically pure p-hydroxysilanes.56 One reliable route is the Cram controlled addition of nucleophiles to a-silyl ketones,6 but such an approach is complicated by difficulties in the preparation of (a-silylalkyl)lithium species or the corresponding Grignard reagents. These difficulties have been resolved by the development of a simple method for the preparation and reductive acylation of (a-chloroalkyl)silanes.7... 

Mg Si bonds have long been inferred in reactions that generate hexaorganodisilanes from halo(triorgano)silanes and either a Grignard reagent or Mg metal ( Silico-Barbier reaction). Similarly, the electrochemical reduction of chloro(triorgano)silanes with sacrificial Mg electrodes yields... 

The (dienyl)iron cations of type (248) and (265) are susceptible to reaction with nucleophiles. For the (cyclohexadienyl)iron cations, nucleophilic attack always occurs at a terminal carbon, on the face of the ligand opposite to the metal, to afford / -cyclohexadiene products. Typical nucleophiles used are malonate anions, amines, electron-rich aromatics, silyl ketene acetals, enamines, hydrides, and aUyl silanes intramolecular nucleophilic addition is also possible. The addition of highly basic organometaUic nucleophiles (Grignard reagents, organolithiums) is often problematic this may be overcome by replacing one of the iron carbonyl... 

Trimethyl(perfluorophenyl)silane (1) is synthesized by the reaction of the Grignard reagent obtained from bromopentafluorobenzene and magnesium, with chlorotrimethylsilane in diethyl ether (90% yield), or by irradiation of a mixture of bis(trimethylsilyl)mercury and perfluoro-... 

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