50515-45-2Relevant academic research and scientific papers
Imidazo[2,1-b]thiazole derivatives XII. Synthesis and immunoactivity in vitro on human T lymphocyte of several 3-aroylmethyl and 2-aroyl-3-methyl(aryl)-5,6-dihydroimidazo[2,1-b]thiazoles
Robert,Hassanine,Harraga,Seilles
, p. 261 - 271 (2007/10/02)
To estimate the influence of aryl group position on the immunostimulant properties of imidazo[2,1-b]thiazole derivatives, several compounds were obtained and tested, versus tetramisole hydrochloride, on the mobilisation of CD2 receptor by human T lymphocyte. The synthesis use the action of monobrominated β-diketones on the 2-mercaptoimidazoline. So, 1-aryl-4-bromobutane-1,3-diones lead to 3-aroylmethyl-5,6-dihydroimidazo[2,1-b]thiazoles 4. Same, 1-aryl-2-bromobutane-1,3-diones and 1,3-diaryl-2-bromopentane-1,3-diones give respectively 3-aroyl-2-methyl-5,6-dihydroimidazo[2,1-b]thiazoles 5 and 3-aroyl-2-aryl-5,6-dihydroimidazo[2,1-b]thiazoles 6. Better yields are obtained when the reaction presents two steps. The first one, realized in acetone at room temperature, leads to an intermediate S-substituted 4,5-dihydroimidazole which, in second step, is cyclized in imidazo[2,1-b]thiazole compound via an unisolated carbinolamine. This one explains the univocal formation of 5 derivatives and the feasible blending in case of 6. The immunoactivity of several imidazothiazoles 4, 5 and 6 is lower that them of 6-aryl substituted compounds and particularly that the levamisole which is the reference product in this series.
12-Te-5 Pertelluranes from 1,2-Oxatellurolyl-1-ium Halides. Synthesis, Structure, and Reactivity. The Quest for Delocalization in 10-Te-3 Telluranes and 12-Te-5 Pertelluranes of Thiathiophthene Structure
Detty, Michael R.,Luss, Henry R.,McKelvey, John M.,Geer, Susan M.
, p. 1692 - 1700 (2007/10/02)
The oxidative addition of chlorine or bromine to 1,2-oxatellurolyl-1-ium chlorides or bromides, respectively, at 0 deg C occurs rapidly to give 12-Te-5 pertelluranes.The structure of 3,5-diphenyl-1,2-oxatellurolylium tribromide (9) was determined unambiguously by single-crystal X-ray crystallographic analysis.Pertelluranes were neutral in solution (CH2Cl2), as determined by conductance studies.The pertelluranes were easily reduced electrochemically to halide ions and the oxatellurolylium halide and were susceptible to nucleophilic attack by Michael addition on the enone segment.Spectroscopic and crystallographic comparison of the pertelluranes with the corresponding oxatellurolylium halides and of dioxatellurapentalenes with the corresponding pertellurane analogues suggested ionic bonding between Te and the halides or O for all four of these systems.Theoretical treatment with CNDO/2 calculations by the program GEOMORV suggested ionic bonding of O and halides to the Te with little ?-delocalization involving Te-O and Te-C bonds in both the tellurane and pertellurane systems.A low-lying ?* LUMO in the pertelluranes was predicted, consistent with the susceptibility to nucleophilic attack, as observed experimentally.
Mono-C-methylation of β-Dicarbonyls with Dimethyl Sulphate and Potassium Carbonate
Raju, N. Ranga,Murthy, M. Sreerama,Rao, E. Venkata
, p. 258 - 259 (2007/10/02)
Methylation of β-dicarbonyls, RCOCH2COR' where R and R' are substituted or unsubstituted phenyl groups, with dimethyl sulphate and potassium carbonate results in the formation of mono-C-methyl derivatives at the active methylene group.
The Allopolarization Principle and its Applications, VI. The Alkylation of Enolate Anions: Polarity and Regioselectivity
Gompper, Rudolf,Vogt, Hans-Hubert,Wagner, Hans-Ulrich
, p. 1644 - 1652 (2007/10/02)
The O/C methylation ratio in the reaction of sodium enolates with dimethylsulfate depends on the polar (electronic) effect of substituents.The relative ?-charge density Px/y = lx/ly can be used as a measure for the polarity of ambifunctional anions; in case of enolate anions PO/C = lO/lC.The change of the regioselectivity Sf = log QO/QC in the alkylation of enolates is a function of a change in the polarity PO/C; ΔSf=f(ΔPx/y).The polar effect of substituents influences the charge control during the alkylation process via a change of the polarity of the enolate system: The higher the polarity of the anion, the stronger the charge control and the higher the yield of enol ether (O-alkylation). - Keywords: Alkylation, Enolate Anions
The Allopolarization Principle and its Applications, IV. Substituent Effects in the Methylation of Enolate Anions
Gompper, Rudolf,Vogt, Hans-Hubert
, p. 2866 - 2883 (2007/10/02)
The ratio of O- and C-methylated products in the reaction of the sodium salts of acetophenones 1, propiophenones 3, phenylacetones 5, β-dicarbonyl compounds 12, α-cyanocarbonyl compounds 13, acetaldehyde, propionaldehyde, and diethylketone with dimethyl sulfate, methyl iodide, and trimethyl phosphate in HMPTA has been determined with regard to the effect of substituents.In some cases the influence of solvents, concentration and temperature has also been studied.
