Trimethylsilylations trimethylsilyldiethylamine

Me3SiNEt2- Trimethylsilyldiethylamine selectively silylates equatorial hydroxyl groups in quantitative yield (4-10 h, 25°). The report indicated no reaction at axial hydroxyl groups. In the prostaglandin series the order of reactivity of trimethylsilyldiethylamine is Cii > Ci5 C9 (no reaction). These trimethylsilyl ethers are readily hydrolyzed in aqueous methanol containing a trace of acetic acid. The reagent is also useful for the silylation of amino-acids. ... 

Trimethylpyridine, 61, 62 N-Trimethylsilylamides, 204 Trimethylsilyl azide, 276, 542 Trimethylsilylcarbene, 544 Trimethylsilyl cyanide, 542-543 Trimethylsilyldiazomethane, 543-544 Trimethylsilyldiethylamine, 544-545 Trimethylsilyl enol ethers, 125, 538 N-(Trimethylsilyl)glycine trimethyl silyl... 

Trimethyl phosphite, 110, 315—316 Trimethylsilyl azide, 316 Trimethylsilyldiethylamine, 317 Trimethylsilyl enol ethers, 310-311 Trimethylsilyl ethers, 24 Trimethylsilylimidazole, 148 Trimethylsulfonium iodide, 124... 

Reaction with trimethylsilyldiethylamine Trimethylsilyl esters of N-trimethylsilylamino acid 28, 29... 

Coad [82] on the formation of derivatives in the column by consecutive insertion into it of (1) a sample of the compound to be analysed and (2) a reagent, suggested using this method to form TMS derivatives. The method was applied to the analysis of polyols, acids and oxyacids. As the donor of the TMS group a mixture of N,0-bis(trimethylsilyl)-acetamide, trimethylsilyldiethylamine and hexamethyldisilazine was used. Fig. 1.14 shows a chromatogram of the TMS derivatives of polyols, obtained in the analysis of a mixture of polyols performed in accordance with the method proposed by Esposito... 

Amino acids from the hydrochlorides. Amino acids can be liberated from the hydrochlorides or hydrobromides by treatment with trimethylsilyldiethylamine in DMF or with bis(trimethylsilyl)acetamide (1, 61 2, 30 3, 23-24) in THF. Average yields exceed 96%. 

Conjugate Addition. Conjugate addition of trimethylsilyl diethylamine to enones gives /3-amino silyl enol ethers. Thus, in the presence of catalytic amounts of trimethylsilyl triflate, trimethylsilyldiethylamine adds to ethyl vinyl ketone in a 1,4-fashion. The reaction requires 50 mol % excess of trimethylsilyldiethylamine, and proceeds in ether at room temperature under nitrogen. The product Af,A -diethyl-3-[(tiimethylsilyl)oxy]-( )-2-pentamine is distilled out under reduced pressure in 45% yield (eq 18). The major product is the -enol ether containing approximately 5% of other trimethylsilyl ether isomers. 

Silylation of Amines. While there are several effective methods for preparation of Af-(trimethylsilyl)amines, only a few successful procedures for Af,Af-bis(trimethylsilyl)alkylamines synthesis have been reported. If silylation of ethylamine is attempted with trimethylsilyl chloride, only 13% of NJ -bis(trimethylsilyl)ethylamine is obtained in addition to the major product iV-(trimethylsilyl)ethylamine. However, N,N-bis(trimethylsilyl)amines can be prepared by silylation of monosi-lylamines with trimethylsilyldiethylamine in the presence of catal3Tic ammonium sulfate or ammonium chloride. Another convenient method for the preparation of Af,A-bis(tri-methylsilyl)alkylamines has recently been reported. There trimethylsilyldiethylamine has been found to be effective in the conversion of primary amines, especially aromatic systems, and their monotrimethylsilyl derivatives into the corresponding bistrimethylsilyl products in high yields. For example, when isopropyl amine (or aniline) is refluxed with 1.1 equiv of trimethylsilyldiethylamine and 1.15 equiv of methyl iodide in toluene for 4 h, bis(trimethylsilyl)isopropylamine [or bis(trimethylsilyl)aniline] can be obtained in 99% yield (or 88% yield based on GC) (eqs 16 and 17). 

Trimethylsilyldiethylamine is a viable alternative to trimethylsilyl ketene acetals or halo esters for the preparation of iV,ATdialkylamino esters. A convenient one-pot method for the preparation of these compounds has been recently reported. The new route is based on aminoalkylation of aldehydes in the presence of (trimethysilyl)dialkylamine and a functionalized zinc reagent [BrZn(CH2)nC02R]. The protocol requires that an aldehyde be treated with a eightfold excess of 5M ethereal LiC104. Trimethylsilyldiethylamine is added... 

Among the main commercial silylation agents, we can mention N,0-bis(tri-methylsilyl)trifluoroacetamide (BSTFA) to which is generally added 1% of trimethyl-chlorosilane (TMCS), the latter playing the role of a catalyst in the reaction, n-methyl-n-(trimethylsilyl)trifluoroacetamide (MSTFA), n-trimethylsilyldiethylamine (TMSDEA), N,0-bis(trimethylsilyl)acetamide (BSA), generally used in mixture with trimethylchlorosilane, and l-(trimethylsilyl)imidazole (TMSl). These molecules are presented in Figure 1.2. 

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