Silylmagnesiums

Both silylmagnesium and silylaluminium species add to terminal alkynes in the presence of a transition-metal catalyst with high regio- and stereoselectivity. For example, platinum-catalysed silamagnesiation (3) followed by aqueous quenching provides exclusively ( )-l-silylalk-l-enes. 

Silyl enol ethers, 23, 77, 99-117,128 Silyl enolates, 77 Silyl peroxides, 57 Silyl triflate, 94 Silyl vinyl lithium, 11 (E)-l -Silylalk-1 -enes, 8 Silylalumimum, 8 Silylation, 94 reductive, 26 a-C-Silylation, 113 O-Silylation.99,100 / -SilyIketone, 54 non-cydic, 55 Silylmagnesium, 8 Silyloxydienes, 112 Sodium hexamethyldisilazide, 89 Sodium thiosulphate pentahydrate, 59 Stannylation, see Hydrostannylation Stannylethene, 11 (Z)-Stilbene, 70 (E)-Stilbene oxide, 70 /3-Styryltrimethylsilane, 141 Swern oxidation. 84,88... 

Two types of reaction allow the synthesis of silylmagnesium compounds ... 

In others, however, other pathways are probably involved, for example involving electron transfer mechanisms or silylmagnesium intermediates, and sometimes giving products different from, or unobtainable by, the two-step procedure. For example, reactions of aromatic carbonyl compounds with magnesium and chlorotrimethylsilane in hexametapol result in silylation at both carbonyl carbon and carbonyl oxygen ... 

Reaction of a chlorosilane with elemental magnesium gives rise to a disilane as a coupling product, although a silylmagnesium species is postulated as an intermediate. 

Aminosilyl)magnesium species are obtained by reaction of the silyllithiums with /-PrMgBr (Scheme 8). The silylmagnesium reagents are milder... 

The silylmagnesium reagent PhjSiMgBr, which is formed by the addition... 

Organosilyl magnesiums are synthesized via halo- or organohalosilanes with Mg metal. Disilanes are produced, suggesting that an intermediate silylmagnesium may be formed. The best results are obtained when chloroarylsilanes are reacted in tetrahydrofuran (THF). Chloroalkylsilanes, such as MejSiCl, react only under specific conditions. These reactions are only useful for disilanes (see also 5.2.3.4) Si—Mg bonded compounds are formed only as reactive intermediates. Older work is reviewed in ref. 1. newer work in refs. 2-6. 

The slow reaction of Hg(SiMc3)2 with Mg metal produces a silylmagnesium in... 

The silylmagnesium product was not isolated the Si—Mg bond is established by further reaction ". ... 

Coupling of Halosilanes with Silyl Anions 467 Coupling of chlorosilane with silyllithium 467 Coupling of chlorosilane with silylpotassium 468 Coupling of chlorosilane with a silylmagnesium reagent 469... 

To a suspension of lithium (granular, 1.66 g, 239 mmol) and THF (50 mL) was added a solution of chlorodimethylphenylsilane (10.0 mL, 60.5 mmol) in THF (10 mL) dropwise over 20 min at 0°C. After stirring for 4 h, the resulting mixture was filtered to remove excess lithium. To this silyllithium solution was added 60 mL (60.6 mmol) of a 1.01 M solution of isopropylmagnesium bromide in diethyl ether dropwise over 20 min at 0°C to give a silylmagnesium reagent. 

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