'The development of a new, direct method for the preparation of dibenzo[a,e]cycloocta-1,5-dienes from phenylacetaldehyde by a double ortho Friedel-Crafts alkylation is described. When benzaldehyde (2b) is treated with trimethylsilyl iodide (3), a,n-diiodotoluene (6) is formed in high yield via the intermediacy of a-iodobenzyl trimethylsilyl ether (4b). Treatment of phenylacetaldehyde (%a) with ...

The aim of the present research work was to determine the Phyto-constituents in fraction collected from ethanolic extract of Pericampylus glaucus leaf using the GC and Mass spectrometry. The Phyto-chemical screening of fraction from ethanolic extract of Pericampylus glaucus leaves were carried out with the help of Perkin-Elmer GC followed by Mass Spectrometry. The GC-MS chromatogram of Pericamp...

A highly specific method is described for measuring the testosterone:epitestosterone ratio in equine urine by gas chromatography-mass spectrometry (GC-MS) with stable isotope internal standards. The procedure was based on Serdolit Pad-1 resin extraction, enzymatic hydrolysis, and chemical derivatisation prior to instrumental analysis. The mixed derivatives, 3-trimethylsilyl-17-pentafluorophenyl...

Tetramethylsilane reacts with 2,2,2-trifluoroethanol (TFE) in the presence of a cationic platinum(II) catalyst [(NN)PtMe(TFE)]+ (NN = 1,2-bis(3,5-dimethylphenylimino)butane). Catalytic Si-C bond heterolysis results in the formation of the trimethylsilyl ether, Me3SiOCH2CF3, accompanied by liberation of one equivalent of methane. Preliminary experiments suggest that a rate-determining C-H bond a...

An improved method for a suitable derivatization of polyhydroxylated steroids having one or two tert-hydroxyl groups at the 5beta-, 14alpha-, 17alpha-, 24-, and/or 25-positions by capillary gas chromatography (CGC) is described. By using trimethylsilyl triflate as a silylating reagent and 2,6-lutidine as a catalyst, each of 5beta-cholane and 5alpha-cholestane series of steroids was successfully...

Me(3)SiI-promoted reaction of salicylic aldehydes with β-dicarbonyl compounds provided a facile way to construct 4H-benzopyrans in moderate to good yields. This tandem reaction proceeds with high efficiency through nucleophilic addition, silyl enol ether formation, substitution, reduction, and intramolecular nucleophilic cyclization.

Vaucheriaxanthin is 19'-OH and not 19-OH neoxanthin. This structural conclusion was borne out by mass, PMR and infrared (IR) spectra from the free pigment and its derivatives (vaucheriaxanthal, vaucheriaxanthal-diacetate, vaucheriaxanthal-diacetate-mono (trimethylsilyl) -ether, vaucheriaxanthintriacetateand triacetate-monosilanate, vaucheriaxanthin-dimethylether) and by comparison of the charac...

We describe the preparation of [2,4,16,16-2H4]estradiol-17 beta. The method for quantitative determination of subpicomole amounts of estradiol-17 beta (trimethylsilyl ether derivatives) by gas-liquid chromatography-mass spectrometry with multiple ion detector and with [2H4]estradiol-17 beta as the carrier is presented and characterized. Values for serum samples, as measured by radioimmunoassay ...