نتایج جستجو برای: trimethylsilyl ethers
تعداد نتایج: 8562 فیلتر نتایج به سال:
1. A gas-liquid-chromatographic procedure is described which permits separation and identification on the same chromatogram of a wide range of substances occurring in urine or tissue extracts. The method uses hydrogen flame ionization, which detects organic compounds whether free or conjugated with no requirement for specific reactive groups. 2. For chromatography, carboxyl groups are quantitat...
Loss of the A ring in the electron-impact mass spectra of the trimethylsilyl (TMS) derivatives of several cholesterol oxidation products is accompanied by intramolecular migration of the 3-O-TMS group to the charge-retaining portion of the molecule. Linked-scan techniques (B/E and B(2)/E) were used to establish the fragmentation processes leading to the formation of the rearrangement ion. The T...
Structurally different trimethyl silyl ethers are oxidized with Bu4/NIO4 in the presence of AlCl3 and BF3 as catalysts in CH3CN and CHCl3 under reflux conditions. The corresponding carbonyl compounds are isolated in good yields.
The direct synthesis of 1,1?,2,2?-tetralithioferrocene from 1,1?,2,2?-tetrabromoferrocene is reported. In addition, the related 1,1?,2,2?,3,3?-hexalithioferrocene also described, prepared directly 1,1?,2,2?,3,3?-hexabromoferrocene. These lithioferrocenes may be isolated as orange red (tetralithio) and (hexalithio) powders, respectively. When these are in situ reacted with chlorotrimethylsilane,...
Starting from tris(trimethylsilyl)silane the novel 2-chloro-3,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazenium-tetrachloridogallate salt (7) was prepared in a six step synthetic procedure including the synthesis of N-tris(trimethylsilyl)silyl-aminodichlorophosphine (4) and 1,3-dichloro-2,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazane (5). All intermediate products along the re...
A general procedure for the nucleophilic addition of organozinc halides with nitrones in the presence of trimethylsilyl chloride has been developed. Trimethylsilyl chloride was found to be both an indispensable reaction promoter and a ready hydroxylamine protective agent in these reactions. The produced O-(trimethylsilyl)hydroxylamines can be easily reduced into corresponding amines just by a z...
The selectivities of nucleophilic substitution reactions of tetrahydropyran acetals promoted by trimethylsilyl trifluoromethanesulfonate depend upon the reaction solvent. Polar solvents favor the formation of S(N)1 products, while nonpolar solvents favor S(N)2 products. Trichloroethylene was identified as the solvent most likely to give S(N)2 products in both C- and O-glycosylation reactions.
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