Rert-butyldimethylsilyl

This strategy was very recently used for the total synthesis of 5-Araneosene. In the first step of the synthesis, methyl rert-butyldimethylsilyl ketone 47 was treated with 2-propenyllithium 48 in ether and then with 2-isopropylallyl bromide 49 in THF to give the (Z)-enol silyl ether 50 in 82% yield. The sequence of reactions that leads to 50 includes (1) carbonyl addition of 48, (2) Brook isomerization and (3) allylation of the resulting ally lie lithium reagent (equation 18) ". ... 

The isocyanide method of reduction has been applied successfully for preparing a series of diversely protected 1,4-anhydroalditols 188 l,4-anhydro-5-O-tert-butyldimethylsilyl-2,3-0-isopropylidene-D-ribitol (56, 81%), l,4-anhydro-5-0-terf-butyldimethylsilyl-6-deoxy-2,3-0-isopropylidene-D-allitol (57,87%) and -l-talitol (58,87%), 1,4-anhydro-2- 0-rert-butyldimethylsilyl-3,5- 0 -isopropylidene-... 

One of the most popular methods of single-stage amino acid derivatization at present is their conversion to N,0 S) err-butyldimethylsilyl derivatives [the reagent rert-butyldimethylsilyl trifluoroacetamide (MTBSTFA) or its A-Me analog]. Another way, which was proposed at the beginning of the 1970s is based on amino acid interaction with dimethylformamide di-alkylacetals (CH3)2NCH(OR )2 (R = Me, Et, Pr, iso-Pr, Bu, Am) with formation of A-dimethylaminometh-ylene derivatives of amino acids esters ... 

A 2-cyclopropyl-l,3-dithiane derivative reacted with butyllithium followed by fert-butyl-chlorodimethylsilane at low temperature to give the 2-rert-butyldimethylsilyl-2-cyclopropyl-l, 3-dithiane derivative in 36% yield. ... 

Two-dimensional GC was employed for the analysis of chiral PCBs in foods such as milk, cheese, and salmon. A new (3-CD derivative (permethylated-(3-CD/hydroxy-termination silicone oil) was employed for the efficient extraction of polybrominated diphenyl ethers in soil. CDs have also been used for the analysis of toxaphene congeners. It was established that permethylated and rert-butyldimethylsilylated-(3-CDs separate different congeners and can be applied for the smdy of the degradation of toxaphens. Another smdy applied two-dimensional GC for the successful separation of toxaphene enantiomers. It was found that the separation efficacy of (3-CD containing columns showed marked differences, depending on the composition of the stationary phase. Capillary columns coated with heptakis-(2,3,6-D-tert-butyldimethylsilyl)-(3-CD or octakis-(quest 2,3,6-tri-D-ethyl)-7-CD were employed for the enantiomer-selective decomposition of toxaphene congeners in rats after intravenous administration. The... 

Unfortunately, none of the hyperbranched polymers smdied to date has demonstrated good mechanical properties. A hyperbranched PC is also expected to be a brittle material, but such a stmcture may prove interesting as a highly functionalized prepolymer for composites, coatings, and other applications. Hyperbranched PCs were synthesized and characterized by Bolton and Wooley. ° The products were prepared by the polymerization of an A2B monomer derived from l,Ll- nT(4 -hydroxyphenyl)-ethane. Silylation of the phenol terminated material with rert-butyldimethylsilyl chloride, followed by degradation of the carbonate hnkages by reaction with lithium aluminum hydride and analysis of the products by HPLC... 

An extensive report (Birkemeyer 2003) has described a painstaking evaluation of 17 different derivatization reactions covering trifluoroacetylation, pentafluorobenzyla-tion, methylation and trimethylsilylation. It was concluded that, for the authors analytes of interest (phytohormones), the N-methyl-N-(rerT-butyldimethylsilyl) trifluo-roacetamide (MTBSTFA) reagent (Figure 5.3) provided the best derivatization for GC/MS analysis with EL This paper contains much useful information on derivatization reagents, reaction conditions etc. 

Field, R.A., Iodine and its interhalogen compounds versatile reagents in carbohydrate chemistry IX a mild and selective deprotection of rert-butyldimethylsilyl (TBDMS) ethers in the presence of various protecting groups using iodine monobromide, Synlett, 3, 311, 1999. 

The Ic2 values (M s ) of the solvolysis of various RsSiOPh in aqueous ethanol at 25 °C were determined under acidic and basic conditions . The size of the silyl groups influences the rate and follows the order listed in entries 55 and 56 of Table 1. The correlation between the Si—O—C angle and the oxygen basicities may be completely different, or even reversed, in comparison with trimethylsilyl and rert-butyldimethylsilyl ethers. The relative hydrolysis rates may be simply controlled by steric hindrance to solvent assistance for the Si—O bond cleavage following the protonation step. 

Hydroxylic groups were confirmed by derivatisation using rerf-butyldimethylsilyl-methyltrifluoroacetamide (TBDMSTA) with 1 % rerT-butyldimethylsilyl chloride (TBDMSCl)... 

SHCHS 2- succinyl-5-enolpyruvyl-6-hydroxy- 3- cyclohexene-1 -carboxylate TBDMS rert-butyldimethylsilyl... 

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