Bistrimethylsilyl ether

Treatment of diadinoxanthin (62) bistrimethylsilyl ether with lithium aluminium hydride affords the bistrimethylsilyl ether of diatoxanthin (94), although similar... 

Metallation-alkylation of chiral formamidine derivatives of 1,2,3,4-tetrahydroisoquin-oline provides optically active 1-alkyl-1.2,3,4-tetrahydroisoquinolines. The formam-idines of 10 optically active amino alcohols have been examined as the chiral auxiliaries and of these, the bistrimethylsilyl ether 2 (S.S-BISPAD) of 1 proved to be the mc>st efficient as well as consistent (equation II). The configuration (S) was established by synthesis of the benzoquinolizine (S)-5, a degradation product of an alkaloid. 

CARBOXYLIC ACIDS Allyltrimethylsilane. Bistrimethylsilyl ether. Chloro-trimethylsilane. Hexamethyldisiloxane. 

AI3-51466 Belsil DM 0.65 Bis-trimethylsilyl oxide Bistrimethylsilyl ether CCRIS 1325 CH7310 Disiloxane, hexamethyl- EINECS 203-492-7 Fluka AG H7250 H7310 HMDSO Hexamethyldisiloxane HMS HSDB 5378 KF 96L NSC 43346 OS 10 Oxybis(trimethyl-silane) Silane, oxybis(trimethyl- SWS-F 221. Coupling agent. 

Alternatively, the bistrimethylsilyl ethers of the bisphenols can be used instead of the alkali salts. This approach has the advantage, since the formation of water and, thus, the risk of a hydrolytic cleavage of C-F bonds is avoided. Furthermore, the purification of the silylated bisphenols can be achieved by simple vacuum distillation. The use of silylated bisphenols also aUows for the preparation of poly(arylene ether)s in the melt (T 130-300 °C) in the presence of catalytic amounts of CsF or KF, thus, avoiding the removal of large amounts of inorganic salts and solvents [94-96] (Fig. 19C). 

Using sulphonic acid ion-exchange resins in ether solvent, selective removal of the trimethylsilyl group from oxygen in bistrimethylsilylated terminal alkynols can be achieved. This method is particularly suitable for low-molecular-weight compounds, where water solubility would make efficient extraction from an aqueous layer difficult. 

Smietana, M., and Mioskowski, C., Preparation of silyl enol ethers using (bistrimethylsilyl)acetamide in ionic liquids, Org. Lett, 7,1037-1039,2001. 

Diastereoselective aldol condensations.1 The reaction of (S)-( - )-2-benzyl-oxyhexanal (2) complexed with TiCl4 with the bistrimethylsilyl enol ether (1) of methyl acetoacetate gives almost exclusively the syn-aldol adduct (3). This reaction... 

Treatment of bistrimethylsilyl enol ethers of glutaric esters with TiC leads to the stereoselective formation of rruns-1,2-cyclopropanedicarboxylic esters (equation 35). ... 

Trimethylsilyl ethers are much more volatile than usual ethers and hence well suited for gas-liquid chromatography. Thus Meinwald6 was unable to effect direct purification of an allenic sesquiterpenoid (1), the defensive substance of the grasshopper Romalea microptera however, the bistrimethylsilyl derivative was purified without difficulty by gas-liquid... 

Hagiwara, H., K. Kimura, and H. Uda High Diastereoselection in the Aldol Reaction of the Bistrimethylsilyl Enol Ether of Methyl Acetoacetate with 2-Benzyloxy-hexanal Synthesis of (-)-Pestalotin. J. Chem. Soc. (London) Perkin Trans. 1, 693 (1992). 

As a-alkylated products are thermodynamically more stable, it is significant to note that these ester carbanions undergo both C-silylation and enol silyl-ation (155) the 0,a-dianions of carboxylic acids furnish bistrimethylsilyl enol ethers (156). 

Furthermore, silylated bisthiophenols, such as (223a,b) were polycondensed with numerous activated difluoro- or dichloro monomers [245,247] and polysulfides of low to moderate molecular weights were obtained. These polycondensations were conducted in bulk with CsF as catalyst. Polymers with an alternating sequence of ether and sulfide bonds were prepared by polycondensation of the diphenol (224a,b) which were used in the bistrimethylsilyl derivatives. The diphenols (224a,b) were synthesized from 4-mercapto-phenol and 2,6-dichloropyridine or 1,4-dichloropyridazine [347]. 

An improved preparation of non-enolizable a-diketones via acyloin condensation is described the acyloin, trapped as its bistrimethylsilyl enol ether, undergoes mild oxidative regeneration by treatment with bromine in dichloromethane or carbon tetrachloride, as shown in Scheme 61. 

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