Ether-solvated contact and separated ion pairs (CIP and SIP) for two lithium reagents, tris(trimethylsilyl)methyllithium (1) and bis(3,5-bistrifluoromethylphenylthio)methyllithium (2), have been characterized and observed for the first time under conditions of slow exchange by NMR spectroscopy, and barriers to interconversion have been measured. A Saunders isotope perturbation experiment was us...

A highly efficient cascade process of Michael-aza-Henry-hemiaminalization-dehydration was established for the construction of enantiopure tetrahydropyridines using the combination of prolinol trimethylsilyl ether and cinchona alkaloid catalysts. This new approach allowed for the application of aliphatic imines, generated in situ from aldehydes and amines. Good yields (up to 90%), high enantio- ...

The protection of functional group is unavoidable in multi-step organic synthesis. Along with tetrahydropyranyl (THP) ethers, t-butyldimethylsilyl (TBDMS) ethers have been widely used for protecting hydroxyl groups. TBDMS ether is more stable to hydrolysis than trimethylsilyl ether, but is still readily cleaved by a variety of selective conditions. The deprotection of TBDMS is usually under mil...

Silylmethyl, tertiary-alkyl, alkenyl, and aryl Grignard reagents underwent intermolecular addition to olefins, such as styrenes, conjugated dienes, and enynes under an air atmosphere to give homologated alcohols. For example, (trimethylsilyl)methylmagnesium chloride and alpha-methylstyrene in ether at room temperature under dry air directly furnished 2-phenyl-4-(trimethylsilyl)-2-butanol in goo...

Sterol composition in muscle and viscera tissues of the marine bivalve Megangulus zyonoensis was investigated. Among 13 different sterols identified by gas chromatography-mass spectrometry of their trimethylsilyl ether derivatives, cholesterol was the most abundant sterol, followed by 24-methylenecholesterol, in both muscle and viscera tissues. In this study, the proportion of brassicasterol, i...

A new, relatively simple method for simultaneous determinations of urinary testosterone and epitestosterone is described. The novel feature is the periodic oxidation of testosterone and epitestosterone glucuronides with sodium metaperiodate. The chromatographic purification of the ether extracts consisted of alumina-column chromatography, followed by thin-layer chromatography on silica gel of f...

Two series of ceramides with either sphingosine (sphing-4-enine) or sphinganine as base and with one of the saturated fatty acids C(16), C(18), C(20), C(22), C(24), C(26), or oleic acid were analyzed as the 1,3-di-O-trimethylsilyl ether derivatives by gas chromatography-mass spectrometry. The fragments formed on electron impact can be divided into three main groups, namely "molecular weight fra...

A reaction-based chemosensor (AF-1) was designed, synthesized and applied as an optical approach for quantitative measurement of F(-) in MeCN. In the presence of F(-), selective fluoride-assisted desilylation instantly gave colorimetric and fluorogenic signals, providing a dual-optical channel for the detection of F(-). (1)H NMR titration was carried out to investigate the desilylation process,...

We describe a gas-chromatographic procedure for determining methylmalonic acid in serum and urine. The sample is acidified and the compound is extracted from it with diethyl ether, derivatized with N,Obis(trimethylsilyl)trifluoroacetamide, and gas chromatographed. Precision and sensitivity of the method were verified by recovery studies and by comparing the resultswith those foran established p...