Kinetic isotope effects for the C-H activation step in phase-transfer halogenations of alkanes

Within the scope of phase-transfer halogenations (Br and I) of alkanes, significant H/D kinetic isotope effects (KIE = 4-5) indicate that hydrogen abstraction is rate limiting. The excellent agreement of computed and experimentally determined H/D KIE as well as trapping experiments support the involvement of trihalomethyl radicals in the activation step.     

Synthesis of α-(4-hydroxyphenyl)-β,β,β-trifluoro-α-alanine derivatives

2,6-Dimethyl- and 2,6-dimethoxy-α-methoxycarbonyl-α-trifluoromethyl-p-methylenequinones have been synthesized. These compounds easily react with ammonia, morpholine, andp-toluidine to afford the corresponding α-(4-hydroxyphenyl)-β,β,β-trifluoro-α-alanine derivatives.     

Synthesis and properties of crystalline fullerene hydrides

The interaction of crystalline fullerence C₆₀ with highly pure hydrogen, which was evolved from hydrides of intermetallic compounds of rear-earth metals and nickel, was studied. Crystalline fullerene hydrides containing from 10 to 30 hydrogen atoms per fullerene molecule were synthesized (1.0–2.5 MPa and 300–673 K). Crystalline hydrides release hydrogen at 800 K with retention of the structure of the fullerene molecule. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2093–2096, October, 1998.     

Synthesis of Fluorine-Containing 2-(1-Aryl-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetic Acids

Acid hydrolysis of ethyl 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetates gives 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2,2-dihydroxyacetic acids which undergo dehydration on heating in toluene to afford 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetic acids. Reactions of the latter with excess morpholine result in replacement of two fluorine atoms in positions 5 and 7 by the amine residues.     

α-Methoxycarbonyl-containing polyflouoalkylsulfenyl chlorides

New -methoxycarbon-containingy polyflnoroalkylsulfenyl chlorides were obtained. Reactions of sulfenyl chlorides containing primary, secondary and tertiary -methoxycarbonyl polyfluoroalkyl groups at the sulfur atom with some unsaturated, carbonyl, arromatic, and heteroaromatic compounds were studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya No 7. pp 1745–1752. July, 1996.     

Problem of a wide variety of products in the Cu(hfac)2-nitroxide system

The stereochemically flexible Cu(hfac)(2) metal-ligand system when combined with polyfunctional nitroxides leads to a variety of solids with varying structure and composition. While investigating the products of Cu(hfac)(2) interaction with spin-labeled pyrazole 4,4,5,5-tetramethyl-2-(1-methyl-1H-pyrazol-4-yl)-imidazoline-3-oxide-1-oxyl, we have isolated a family of (12) heterospin compounds differing in structure and composition in the solid state. In synthetic systems, these compounds often cocrystallize and must be separated mechanically. It is also shown that minor variation of the structure of the solid heterospin complex can substantially change the magnetic properties of compounds.     

Reactions of polyfluorocarbonyl compounds with phenolates

Conclusions Hexafluoroacetone and methyl trifluoropyruvate react under mild conditions with sodium phenolate, sodium alkoxyphenolates, sodium alkylphenolates, and sodium dialkylphenolates to give the ortho-alkylation and ortho,ortho-dialkylation products. In the case of sodium phenolate, the tri-C-alkylation product is also obtained. The second C-alkylation of meta-substituted sodium phenolates was found to be difficult.For previous communication, see ref. [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2849–2852, December, 1987.     

A potent and highly selective inhibitor of human alpha-1,3-fucosyltransferase via click chemistry

Potent inhibitors of fucosyltransferases, and glycosyltransferases in general, have been elusive due to the inherent barriers surrounding the family of glycosyltransfer reactions. The problems of weak substrate affinity and low catalytic proficiency of fucosyltransferase was offset by recruiting additional binding features, in this case hydrophobic interactions, to produce a high affinity inhibitor, 24, with Ki = 62 nM. The molecule was identified from a GDP-triazole library of 85 compounds, which was produced by the Cu(I)-catalyzed [2 + 3] cycloaddition reaction between azide and acetylene reactants, followed by in situ screening without product isolation.     

Synthesis and reactions of 6-hydroxy-2,4-dimethyl-1,3-benzodioxane

The reaction of hydroquinone and acetaldehyde in a mixture of acetic and hydrochloric acids (31) at 0–5 °C gives 6-hydroxy-2,4-dimethyl-1,3-benzodioxane, which forms ethers and esters at the hydroxy group, undergoes diazo coupling, and, under the influence of acids, undergoes polycondensation with opening of the 1,3-dioxane ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1195–1198, September, 1983.     

Preparation of substituted 3-hydroxy-3-trifluoromethyl-2(3H)benzofuranones

Conclusions When heated with methyl trifluoropyruvate in aprotic solvents and acetic acid above 120°C it was found that phenols (not containing electron acceptor ring substituents) regioselectively formed ortho-C-alkylation products which could be lactonized to 3-hydroxy-3-trifluoromethyl-2(3H)benzo[b]furanones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2511–2517, November, 1987.