Silane vinyl dimethyl

A frequently asked question is whether the silicon needs to have three surface reactive groups. The tri-functionaUty arose initially because the vinyl trichlorosilane (and hence the trialkoxy derivatives) was readily prepared. It is more difficult and expensive to make less functional molecules such as vinyl dimethyl mono-alkoxy silane. There is no definitive information on how such compounds might compare with the trialkoxy ones. 

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

The 0/7/fo-alkylation of aromatic ketones with olefins can also be achieved by using the rhodium bis-olefin complex [C5Me5Rh(C2H3SiMe3)2] 2, as shown in Equation (9).7 This reaction is applied to a series of olefins (allyltrimethyl-silane, 1-pentene, norbornene, 2,2 -dimethyl-3-butene, cyclopentene, and vinyl ethyl ether) and aromatic ketones (benzophenone, 4,4 -dimethoxybenzophenone, 3,3 -bis(trifluoromethyl)benzophenone, dibenzosuberone, acetophenone, />-chloroacetophenone, and />-(trifluoromethyl)acetophenone). 

While method A furnished only dimethyl(vinyl)silane (see Section IILC.l.a), the Wurtz reaction (method B) in an inert solvent gave a mixture of products which stem either from the a-elimination generating 3a or from the C,C coupling process leading to 158 (equation 38)55. It is assumed that 3a forms 1,1-dimethylsilirane by 1,3-C,H insertion (cf equation 23) and that C,C and Si,C cleavage of this sensitive ring system by (trimethylsi-lyl)methyl sodium is responsible for the formation of 159-161 (combined yield 32%). It is obvious that, due to the complexity of this reaction, method B cannot serve as a versatile entry into the chemistry of 3a. 

Vinylchlorosilanes undergo Friedel-Crafts alkylation with aromatic compounds in the presence of Lewis acids to give 2-(chlorosilyl)ethylarenes [Eq. (17)].lb 32,33 The reactivity of vinylchlorosilanes for the alkylation of aromatic compounds is slightly lower than that of allylchlorosilanes.lb 3,32 The reactivity of vinylsilanes for alkylation depends on the substituents on the silicon of the vinylsilane. The reactivity of vinylchlorosilanes decreases in the following order dichloro(methyl)vinyl-silane > trichlorovinylsilane > chloro(dimethyl)vinylsilane. The alkylation of mono-substituted benzenes such as toluene, chlorobenzene, and biphenyl with di-chloro(methyl)vinylsilane (lc) at 75-80 °C for 2h affords alkylated products in 50-63% yields.32... 

The conditions giving the best yields for the vinylation with trimethylvinylsilane were applied to the coupling reaction of 1-trimethylsilyl-l-octene [Eq.(7)]. However, the silicon reagent was recovered totally intact. We considered that the polarization of the C-Si bond of this reagent was lowered by the hexyl substituent. Accordingly, to induce the polarization of the Si-C bond, we replaced one to three methyl(s) on Si by fluorine(s) and were pleased to find that fluoro(dimethyl)silane (n = 1) or difluoro(methyl)silane (n = 2) was reactive enough [8]. 

Analogously, the gas-phase thermal decomposition of trifluoro(l,l,2,2-tetrafluoroethyl)silane (at 140-200 C) or trimethyl(l,l,2,2-tetrafluoroethyI)silane (at 300-370°C) generated di-fluoromethyl(fluoro)carbene which underwent addition to alkenes to give 1-difluoromethyl-l-fluorocyclopropane 8. ° (Z)- and ( )-But-2-ene were cyclopropanated stereospecifically, and allylic C-H insertion was not observed. With dimethyl(vinyl)silane or allyl(dimeth-yl)silane, however, the carbene underwent both double bond addition and Si-H insertion. ... 

Various photoreactions in which the silicon atom plays a less important role have been reported. The isolation of trans-1,2-diphenyl-4,4,5,5,6,6-hexamethyl-4,5,6-trisilacycloheptene (185), formed by irradiation of the corresponding cis-isomer (186), has been described the stability of this system is attributed to the long silicon-silicon bond lengths.Evidence for the intermediacy of a photochemically generated metastable trans-cycloalkene has also been reported in l,l,4,4-tetramethyl-l,4-disilacyclohept-2-ene. A novel [,2 + 2] photocycloaddition to give the bicycles (187) has been reported in the diallylsilanes (188) in the presence of 1,4,-dicyanonaphthalene. Intramolecular [ 2 + 2] photoaddition has also been observed in bis- and tetrakis-(4-vinyl-benzyl) silanes and their germane analogues,and the oxetanes (189) and (190) have been prepared by irradiation of 1,1-dimethyl-2,5-diphenylsilacyclopentadiene in the presence of benzophenone. 

See Styrene/butadiene polymer Ethenylbenzene, polymer with 2-propenamide. See Styrene/acrylamide copolymer Ethenylbenzenesulfonic acid, sodium salt, homopolymer 4-Ethenylbenzenesulfonic acid sodium salt, homopolymer. See Sodium polystyrene sulfonate 4-Ethenylcyclohexene 4-EthenyM -cyclohexene. See 4-Vinylcyclohexene Ethenyidimethoxymethylsilane. See Vinylmethyidimethoxysilane 1 -Ethenyl-1,5-dimethyl-4-hexenyl benzeneacetate. See Linalyl phenylacetate 1 -Ethenyl-1,5-dimethyl-4-hexenyl 3-phenyl-2-propenoate. See Linalyl cinnamate Ethenyl ethanoate. See Vinyl acetate 6-Ethenyl-6-(methoxyethoxy)-2,5,7,10-tetraoxa-6-silaundecane. SeeVinyltris(2-methoxyethoxy) silane... 

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