Disilazane, hexamethyl-, trimethylsilylation

Imidazole werden durch die gangigen Silylierungsreagentien wie z. B. Hexamethyl-disilazan 1-Trimethylsilyl-imidazol 85%)885 886 oder Chlorsilan/Base [l-Dimethyl-( 1,1,2-trimethyl-pro-pyl)-silyl-imidazol (mit Triethylamin als Base 76%)887 1-Trimethylsilyl-imidazol (aus Natrium-imidazolid mit Chlor-trimethyl-silan 95%)]792 in 1-Position silyliert. 

Sodium bis(trimethylsilyl)amide (hexamethyl disilazane sodium salt) [1070-89-9] M 183.4, m 165-167 (sintering at 140 ). It can be sublimed at 170 /2 Torr (bath temp 220-250°) onto a cold finger, and can be recrystd from CgHg (sol lOg in lOOmL at 60°). It is slightly soluble in Et20 and is decomposed by H2O. [Chem Ber 94 1540 1961.]... 

Lithium bis(trimethylsilyl)amide (LiHMDS) Disilazane, 1,1,1,3,3,3-hexamethyl-, lithium salt (8) Silanamine, 1,1,1 -trimethyl-N-(trimethylsilyl)-, lithium salt (9) (4039-32-1)... 

Conversion of sugars into their O-trimethylsilyl (Me3Si) derivatives is most commonly achieved by reaction in pyridine with hexamethyl-disilazane (1) and chlorotrimethylsilane (2) according to equation (I). 

Die Addition von Aminen an die Isocyanat-Gruppe vom Phosphorsiiure-dichlorid-isocy-anat (Bd.XII/2, S.502) kann auf Hexamethyl-disilazan (in Ether bei max. 25°, 2 Stdn.) iibertragen werden. Man erhalt Phosphorsdure- (bis- [trimethylsilyl]-aminocarbo-nyl)-amid -dichlorid in 8 l°/0iger Ausbeute253. 

Trimethylsilyl enol ethers." This reagent in conjunction with hexamethyl-disilazane converts ketones and aldehydes into trimethylsilyl enol ethers rapidly and in high yield at room temperature or below. The thermodynamically more stable products predominate. A useful feature is that ketones can be selectively silylated in the presence of an ester group. 

Sodium bis(trimethylsilyl)amide NaHMDS Disilazane, 1,1,1,3,3,3-hexamethyl-,... 

Sodium bis(trimethylsilyl)amide (hexamethyl disilazane sodium salt) [1070-89-9] M 183.4, m 165-... 

After considerable research, which examined a wide variety of different derivatives, trimethylsilylation has emerged as the procedure of popular choice for steroid and steroidlike compounds. Pure compounds or biological extracts containing 3 (3-hydroxyl groups can be readily silylated by treatment with A,G-bis-trimethylsilyltrifluoro-acetamide containing 1 % trimethylchlorosilane at 60°C for 30 min, with or without added pyridine. A,G-bis-tri-methylsilyltrifluoroacetamide, under some circumstances, can also be used alone or with a mixture of hexamethyl-disilazane and trimethylchlorosilane (10 10 5 v/v/v) at 60°C for 30-60 min. The trimethylsilyl derivatives separate well on capillary columns carrying apolar stationary phases. The derivatives also provide excellent electron-impact mass spectra. 

The relative retention times of the trimethylsilyl (TMS) ethers in Table III are related to the TMS ether of methyl deoxycholate as 1.00. The TMS ethers were prepared from a mixture of trimethylsilyl chloride, hexamethyl-disilazane, and dry pyridine according to Makita and Wells (61) to assure the formation of the complete derivative (cf. Chapter 5 for a discussion of the preparation of partial TMS derivatives). These TMS ethers are generally eluted more rapidly from the column than the free alcohols the TMS ethers of the equatorial 3 3-ols of the allocholanates are generally retained on the column longer than the corresponding 3/3 ethers of the 5/3-epimers (60). On the other hand, the TMS ethers of the allo-3a-ol, 3a,7a-diol, 3a,7a,12a- and 3a,6/3,7/3-triols are eluted from each of the three phases before their respective 5/3-cholanates. However, the TMS ether of methyl allodeoxycholate is eluted before the TMS ether of methyl deoxycholate on QF-1, but not on OV-1 or OV-17 (60). Hoshita et al. (39) observed that the TMS ethers of... 

Bis(trimethylsilyl)acetamide. Bis(trimethylsilyl)acetamide (BSA) has been formulated as iV,iV-bis(trimethylsilyl)acetamide as well as the imidate form. The NMR spectra of a number of silylamide derivatives ( C, Si, and 0) have been investigated. Whereas BSA is seen to exist in the imidate form, some analogs, for example bis(trimethylsilyl)formamide, exist in the IVW-bis(trimethylsilyl) form, and the product obtained by the interaction of l,2-bis(chlorodimethylsilyl)ethane with BSA is also clearly in the alternative foim Trimethylsilyl derivatives of hydroxamic acids are formed in reactions using hexamethyl-disilazane and are similar in structure to BSA. This entry will concentrate on examples from the more recent literature. 

A study of the preparation of trimethylsilyl derivatives of amino acids and peptides using trimethyl-silyldiethylamine, bis-(trimethylsilyl)acetamide, N-trimethylsilyl-N-methy1acetamide, and hexamethyl-disilazane as the silylating agents. 

Related Reagents. A, 0-Bis(trimethylsilyl)acetamide N,N -Bis(trimethylsilyl)urea Cyanotrimethylsilane Hexamethyl-disilazane Hexamethyldisiloxane lodotrimethylsilane )V-(Tri-methy lsilyl)imidazole Trimethylsilyl Trifluoromethanesulfonate. 

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