Trimethyl silyl

The distillate was dissolved in a mixture of 350 ml of dry diethyl ether and 45 g of dry triethylamine (dried over powdered KQH). Trimethylchlorosilane (45 g) was added in 20 min with cooling at about 10°C. After standing for 1 h at room temperature the precipitate was sucked off on a dry sintered-glass funnel and rinsed with pentane. The filtrate was concentrated in a water-pump vacuum- The small amount of salt which precipitated during this operation was removed by a second suction filtration. Subsequent distillation afforded the trimethyl silyl ether, b.p. 100°C/15 mmHg, 1.4330, in 944 yield. 

Bis (trimethyl silyl) peroxide (CH2)3SiOOSi(CH2)3 can be used with triflic acid (CF SO H) and acts as an effective hydroxylating agent of aromatics such as toluene, mesitylene and naphthalene (165). Sodium perborate (a safe and inexpensive commercial chemical) can be used in conjunction with the triflic acid to hydroxylate aromatics (166). 

V-trimethyl silyl diethyl-amine [996-50-9] TMSDEA (CH3)3SiNH(C3H3)3... 

V-Trimethyl silyl diethyl amine (TMSDEA) is a stroagly basic silylatiag reageat and is particulady usehil for derivatiziag low molecular weight acids. The reaction by-product, diethylamine, is volatile enough to be easily removed from the reaction medium. 

Silyl Ethers. The preparation of per- O-trimethyl silyl ethers of sucrose is generally achieved by reaction with chi orotrimethyl sil ane and/or hexamethyldisila2ane in pyridine (25,26). However, this reaction is not selective and in general per-trimethyl silyl ethers are only used as derivatives for gas chromatographic studies. 

Conversion to a more facile, sulfur-derived, leaving group can be achieved by treatment with sodium thiosulfate or salts of thio and dithio acids (75,87). Under anhydrous conditions, boron tribromide converts the 3 -acetoxy group to a bromide whereas trimethyl silyl iodide gives good yields of the 3 -iodide (87,171,172). These 3 -halides are much more reactive, even when the carboxyl group is esterified, and can be displaced readily by cyano and by oxygen nucleophiles (127). 

A newer method for the preparation of nitronic esters, namely utilizing the (9-trimethyl-silyl ester, has been reported and these are prepared by the reaction of alkylnitro compounds and (V,(V-bis(trimethylsilyl)acetamide. These nitronic esters also undergo cycloaddition with alkenes to produce isoxazolidines (equation 54) (74MIP41601, 74DOK109, 78ACS(B)ll8). 

Sulfonation of the aromatic ring of l, 2, 2 -trifluorostyrene below 0 C does not give satisfactory yields with chlorosulfonic acid or a sulfur trioxide-dioxane complex Tar forms on heating In contrast, under similar conditions ipso substitution IS facile at the position of a trialkylsilyl or -stannyl group Thus, 4-trimethyl-silyl-T 2, 2 D-trifluorostyrene affords the corresponding trimethylsilyl sulfonate [20] (equation 9)... 

In a formal synthesis of fasicularin, the critical spirocyclic ketone intermediate 183 was obtained by use of the rearrangement reaction of the silyloxy epoxide 182, derived from the unsaturated alcohol 180. Alkene 180 was epoxidized with DMDO to produce epoxy alcohol 181 as a single diastereoisomer, which was transformed into the trimethyl silyl ether derivative 182. Treatment of 182 with HCU resulted in smooth ring-expansion to produce spiro compound 183, which was subsequently elaborated to the desired natural product (Scheme 8.46) [88]. 

To a mixture of vinyl bromide (40 mmol) and the catalyst dichloro-[(R)-Af,N-dimethyl-l-[(.S)-2-(diphenylphosphino)ferrocenyl]ethylamine]-palladium(n) (0.2 mmol) was added an ethereal solution of [a-(trimethyl-silyl)benzyl]magnesium bromide (0.6-1 m, 80 mmol) at —78 °C. The mixture was stirred at 30 °C for 4 days, and then cooled to 0 °C and hydrolysed with dilute aqueous HC1 (3 m). The organic layer was separated, and the aqueous layer was re-extracted with ether. The combined organic extracts were washed with saturated sodium hydrogen carbonate solution and water, and dried. Concentration and distillation gave the chiral allylsilane (79%, 66% ee), b.p. 55°C/0.4mmHg. 

Organoboranes react with a mixture of aqueous NH3 and NaOCl to produce primary amines. It is likely that the actual reagent is chloramine NH2CI. Chloramine itself,hydroxylamine-O-sulfonic acid in diglyme, and trimethyl-silyl azide " also give the reaction. Since the boranes can be prepared by the hydroboration of alkenes (15-16), this is an indirect method for the addition of NH3 to a double bond with anti-Markovnikov orientation. Secondary amines can be prepared by the treatment of alkyl- or aryldichloroboranes or dialkylchlorobor-anes with alkyl or aryl azides. 

One-pot tandem sequences involving 1,4-addition and ISOC as the key steps have been developed for the construction of N and 0 heterocycles as well as of carbocycles [44]. In this sequence, the nitronate arising from 1,4-addition to an a, -unsaturated nitro alkene is trapped kinetically using trimethyl silyl chloride (TMSCl). The resulting silyl nitronate underwent a facile intramolecular 1,3-dipolar cycloaddition with the unsaturated tether (e.g.. Schemes 20-22). 

Monomers contained terminal phenylacetylenes protected with trimethyl-silyl groups and aryl iodides masked as N,hT-dialkyltriazenes. A typical PAM synthesis involved three basic transformations (Scheme 12) ... 

Alternative silylating reagents such as N,0-bis(trimethylsilyl)acetamide 22a (BSA) [39-43], N,0-bis(trimethylsilyl)trifluoracetamide 22b (BSTFA) [44], or N,N-bis(trimethylsilyl)formamide 22c (BSF) [41, 46], in which the N- and O-trimethyl-silyl groups are in equilibrium [45] (Scheme 2.4), are much more powerful silylating reagents [40, 45] but are more expensive than FIMDS 2, because they are usually prepared by heating formamides or acetamides with TCS 14/triethylamine... 

It is obvious that N,0-bis(trimethylsilylated)acetamides or N,0-bis(trimethyl-silylated)formamides 22 or N,0-bis(trimethylsilyl)benzamide 296 should react likewise with the hydrochlorides or hydriodides of primary or secondary amines or with the free amines in the presence of equivalent amounts of e.g., NH4CI or NH4I to give the corresponding amidinium salts. 

Whereas aldehydes such as benzaldehyde or ketones are converted by trimethyl-silylated alkyl- or aryl-mercaptans such as 575, in the presence of catalytic amounts of cyanide, to give high yields to O-trimethylsilyl-hemithioketals such as... 

CoCl2 6H20 [149] or TMSOTf 20 [150-152] in acetonitrile afford Diels-Alder adducts in yields of up to 85%. The dienals 607 are converted by bis(trimethyl-silyl)thiane 601 or bis(trimethylsilyl)selenide 604 and catalytic amounts of BuLi, via 609, to the intramolecular Diels-Alder products 610 in up to 70% yield [153, 154]. 

Trimethylsilyl iodide 17, which can be generated in situ by reaction of trimethyl-silyl chloride (TCS) 14 with Nal in acetonitrile [1], converts alcohols 11, in high yields at room temperature, into their iodides 773a, HI, and hexamethyldisiloxane (HMDSO) 7 [1-8, 12]. Likewise esters such as benzyl benzoate are cleaved by Me3SiCl 14/NaI in acetonitrile under reflux [Ij. Reactions of alcohols 11 with trimethylsilyl bromide 16 in chloroform or, for in situ synthesis of 16 from liBr and TCS 14 in acetonitrile and with HMDS 2 and pyridinium bromide perbromide, proceed only on heating in acetonitrile or chloroform to give the bromides 773 b in nearly quantitative yield [3, 8, 12] (Scheme 6.1). 

Formamide is silylated on heating with HMDS 2 to give N,N-bis(trimethyl-silyl)formamide 22c, which trimerizes on continued heating to 140 °C to give s-triazine 1575, via 1573 and 1574, in 83% yield [78] (Scheme 9.47). 

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