Easy synthesis of heterocyclic carbene complexes by activation of chalcogenopyrones and benzopyrones to pyrylium salts and subsequent addition of carbanion of methoxy(methyl)pentacarbonyltungsten carbene complex

Methylenechalcogenopyran and benzopyran Fischer carbene complexes are easily obtained from commercially available chalcogenopyrones or benzopyrones and carbanion of methoxy(methyl)carbene tungsten complex. The key of the heterocyclic carbene formation is the activation of the carbonyl group by alkylation with alkyl trifluoromethanesulfonate reagent.     

A mild hydrolysis of esters mediated by lithium salts

When treated with amine bases such as triethylamine and various lithium salts in wet solvents, esters are efficiently hydrolyzed to the corresponding acids in good yields. Esters incorporating an α- or β-heteroatom with respect to the ester carbonyl group are hydrolyzed rapidly even at room temperature. To further demonstrate the usefulness of this method, one example is provided where hydrolysis of acetylated camphorsultam is mediated by LiBr.     

羧基丙烯酸酯涂料合成及其防雾性能研究

采用种子乳液聚合法合成了一种互穿网络型羧基丙烯酸酯类聚物乳液，研究了加料方式对羧基分布的影响，结果表明丙烯酸加入到核单体中有利于羧基分布在乳胶粒表面。在体系中引入离子键交联结构提高了乳液涂料的硬度和耐水性能，离子键交联ＰＩＬＮ型涂料具有优良的防雾性能。     

Carbamoylimidazolium and thiocarbamoylimidazolium salts: novel reagents for the synthesis of ureas, thioureas, carbamates, thiocarbamates and amides

Carbamoylimidazolium salts act as efficient N,N-disubstituted carbamoylating reagents. These salts are readily prepared by the sequential treatment of secondary amines with N,N′-carbonyldiimidazole (CDI) and iodomethane. The carbamoylimidazolium salts are more efficient carbamoyl transfer reagents than the intermediate carbamoylimidazoles, as a result of the ‘imidazolium’ effect. Kinetic studies on the base promoted hydrolysis of both carbamoylimidazoles and carbamoylimidazolium salts reveal over a hundred-fold rate acceleration. The salts react with amines, thiols, phenols/alcohols, and carboxylic acids in high yields, without the need for subsequent chromatographic purification of the products, producing ureas, thiocarbamates, carbamates, and amides, respectively. Analogous thiocarbamoylimidazolium salts were also synthesized from secondary amines and N,N′-thiocarbonyldiimidazole (TCDI), followed by methylation with iodomethane.     

Über die Kristallstrukturen von CH3PF2H+AsF6− und CH3PF2H+SbF6− und eine einfache Darstellung von CH3PF2

On the Crystal Structures of CH₃PF₂H⁺AsF₆^? and CH₃PF₂H⁺SbF₆^? and a simple Method for Preparation of CH₃PF₂ A simple method for preparation of CH₃PF₂ from CH₃PCl₂ is reported. The phosphonium salts CH₃PF₂H⁺MF₆^? are obtained by the reaction of CH₃PCl₂ with superacidic systems HF/MF₅ (M = As, Sb). CH₃PF₂H⁺SbF₆^? crystallizes in the space group P1 with a = 548.4(4) pm, b = 695.5(8) pm, c = 960.2(9) pm, α = 94.68(5)°, β = 97.19(6)°, γ = 94.41(6)° and Z = 2. CH₃PF₂H⁺SbF₆^? crystallizes in P1 with a = 554.3(3), b = 724.2(4), c = 970.4(5), α = 94.73(4)°, β = 96.14(5)°, γ = 95.30(4)°.     

Oxidative Methyl Esterification of Primary Alcohols with Iodine‐Mediated Poly[4‐(Diacetoxyiodo)Styrene]

An operationally simple oxidative methyl esterification of primary alcohols in good yields using an iodine‐mediated poly[4‐(diacetoxyiodo)styrene] in methanol at room temperature is described. The polymeric reagent can be regenerated and reused as an environmentally benign reagent.     

Synthesis and properties of chiral ammonium-based ionic liquids

New chiral ammonium-based ionic liquids containing the (1R,2S,5R)-(-)-menthyl group can be easily and efficiently prepared under ambient conditions. The preparation and characterization of trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium salts is reported. The salts have been demonstrated to be air- and moisture-stable under ambient conditions and can be readily used in a variety of standard experimental procedures. The single-crystal X-ray structure of butyldimethyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride has been determined. The chiral, room-temperature ionic liquids have been characterized by physical properties such as specific rotation, density, viscosity, thermal degradation, and glass transition temperature. Trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride prototype ionic liquids have also been found to exhibit strong antimicrobial and high antielectrostatic activities.     

Catalytic olefination of carbonyl compounds. A new versatile method for the synthesis of alkenes

The review is devoted to a new catalytic olefination reaction (COR) discovered by the authors. This is the reaction between N-unsubstituted hydrazones of carbonyl compounds with dihalides CHal₂XY in the presence of copper(i) chloride to give substituted alkenes. Catalytic olefination is versatile. Variation of the carbonyl and olefinating components opens up the way for the synthesis of various classes of unsaturated compounds including those containing functional groups. The reaction mechanism is discussed and a catalytic cycle describing the process is proposed. A model for estimating and predicting the reactivity of halogen-containing compounds in the COR is developed. The relationship between the structure of the carbonyl substrates and their behavior in the title reaction is elucidated.     

Nuclear magnetic resonance spectroscopic study on ionic liquids of 1-alkyl-3-methylimidazolium salts

Chemical shifts of ¹H and ¹³C NMR of series of methylimidazolium salts (MIM⁺, X=Br⁻, BF₄⁻ and PF₆⁻) function on the length of alkyl groups on the ring, type of solvents and the concentration. The bromides series demonstrate more chemical shift variation on H2 upon the change of solvents and concentration. Unexpected H-D exchange reactions were also observed in the MIM⁺Br⁻ by using CD₃OD and D₂O. The exchange rates strongly depend on the length of the alkyl group, which could cause more steric factor to reduce the interaction between deuterium atom from solvent and C2 of the ring.     

Synthesis and tautomeric transformations of 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones

Treatment of 2-(tert-butyl)-1,2,3,4-benzotetrazinium tetrafluoroborates with sodium thiocyanate afforded 2-(tert-butylazo)phenyl isothiocyanates 3, which exist in equilibrium with 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones 3′. The equilibrium depends on the substituents R in the benzene ring: the percentage of the open isomer 3 is about 20% for R = H or Me; for R = Cl or Br, the equilibrium is completely shifted to cyclic isomer 3′. The equilibrium is slow on the time scale of the ¹H and ¹³C NMR experiments. For compounds 3a/3′a (R = H), the spectra at 24 °C show two sets of signals, while those at 0 °C contain only signals for isomer 3′a. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1192–1195, July, 2006.