Me3Si

In the flask was placed a solution of 0.44 mol of butyllithium in about 300 ml of hexane. To this solution were added, with coaling below -20°C, 800, 600 and 400 ml of dry diethyl ether (note 1) in the case of R = CH3, C2H5 and tert.-CuHj or Me3Si, respectively. Subsequently 0.46 mol of the alkyne [in the case of R = CH3, C2H5 a cooled (-30°C) solution in 50 ml of diethyl ether] was added in about 10 min, while keeping the temperature below -20 c. The suspension (in the... 

A trialkylsilyl group can be introduced into aryl or alkenyl groups using hexaalkyidisilanes. The Si—Si bond is cleaved with a Pd catalyst, and trans-metallation and reductive elimination afford the silylated products. In this way, 1,2-bis-silylethylene 761 is prepared from 1,2-dichloroethylene (760)[625,626], The facile reaction of (Me3Si)2 to give 762 proceeds at room temperature in the presence of fluoride anion[627]. Alkenyl- and arylsilanes are prepared by the reaction of (Me3Si)3Al (763)[628],... 

Substituted aroyl- and heteroaroyltrimethylsilanes (acylsilanes) are prepared by the coupling of an aroyl chloride with (Me3Si)2 without decarbonylation, and this chemistry is treated in Section 1.2[629], Under certain conditions, aroyl chlorides react with disilanes after decarbonylation. Thus the reaction of aroyl chlorides with disilane via decarbonylation is a good preparative method for aromatic silicon compounds. As an interesting application, trimel-litic anhydride chloride (764) reacts with dichlorotetramethyidisilane to afford 4-chlorodimethylsilylphthalic anhydride (765), which is converted into 766 and used for polymerization[630]. When the reaction is carried out in a non-polar solvent, biphthalic anhydride (767) is formed[631]. Benzylchlorodimethylsilane (768) is obtained by the coupling of benzyl chloride with dichlorotetramethyl-disilane[632,633]. 

The reaction of benzoyl chloride with (Me3Si)2 affords benzoyltrimethylsi-lane (878)[626,749,750]. Hexamethyldigermane behaves similarly. The siloxy-cyclopropane 879 forms the Pd homoenolate of a ketone and reacts with an acyl halide to form,880. The 1,4-diketone 881 is obtained by reductive elimination of 880 without undergoing elimination of /7-hydrogen[751]. 

Unstrained difluorotetramethyldisilane (84) gives the 1 1 adduct 85 as the main product and the 1 2 adduct 86 as a minor product[78,79]. On the other hand, the dimerization and double silylation of conjugated dienes with (Me3Si)2 catalyzed by PdCl2(PhCN)2 take place at 90" C[80]. Pd(dba)2 without phosphine is an active catalyst for the reaction, which proceeds in DMF to give 87 at room temperature[81], A five-membered ring is formed by the application of the reaction to the di-(2,4-pentadienyl)malonate (69)[82]. 

Double. silylation of the a-diketone 120 with (Me3Si)2 is catalyzed by PdCl2(Me3P)2 to give the l,2-bis(siloxy)ethylene 121 in a good yield[ll7], Hydro.silylation of phenyl isocyanate (122) catalyzed by PdCN affords the /V-... 

Me3Si)2NH, Me3SiCl, Pyr, 20°, 5 min, 100% yield. ROH is a carbohydrate. Hexamethyldisilazane (HMDS) is one of the most common sily-lating agents and readily silylates alcohols, acids, amines, thiols, phenols, hydroxamic acids, amides, thioamides, sulfonamides, phosphoric amides, phosphites, hydrazines, and enolizable ketones. It works best in the presence of a catalyst such as X-NH-Y, where at least one of the group X or Y is electron-withdrawing. ... 

Me3Si)20, PyH TsO, PhH, mol. sieves, reflux, 4 days, 80-90% yield. These mildly acidic conditions are suitable for acid-sensitive alcohols. 

A related example is the reaction of NbCls and thf with (Me3Si)2NN(SiMe3)2 in CH2CI2 to give an 80% yield of [(/Lt-N2) NbCl3(th02 2]- Occasionally an N=N triple bond can be formed within a metal complex, e.g. by reaction of coordinated NH3 with HNO2, but this method is of limited application, e.g. ... 

Ethyl diazoacetate adds endo to Me3Si(C=C)2SiMe3 to give 3-ethoxycarbonyl-4-trimethylsilylethynyl-5-trimethylsilylpyrazole (88JOM247). 

A 1,3,4-triphosphole complex is prepared in the thermally induced regi-ospecific insertion of (t-Pr)(Me3Si)N-C = P into the phosphorus-phosphorus bond of species 108 to yield 109 (01AGE2471). 

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