Ruthenium catalyzed synthesis of secondary or tertiary amines from amines and alcohols

Unsymmetrical secondary and tertiary amines are prepared by the ruthenium catalyzed reaction of alcohols with amines, which provides highly efficient method for synthesis of cyclic amines.     

Intermolecular interaction energy of CH4 trimer by symmetry-adapted perturbation theory

The interaction energy for the cyclic CH₄ trimer is studied in terms of symmetry-adapted perturbation theory. The interaction energy around the van der Waals minimum is dominated by attractive dispersion energy, and the repulsive contribution at the smaller angle region is due to the first-order exchange energy. The total interaction energy is approximated by additive two-body components, because of a mutual cancellation between nonadditive three-body ones.     

Electrooxidation of alcohols in an N-oxyl-immobilized rigid network polymer particles/water disperse system

The electrooxidation of alcohols in an aqueous disperse system with N-oxyl-immobilized poly(p-phenylene benzobisthiazole) network polymer particles (PBZT_NT-N-Oxyl) as a disperse phase was performed successfully in a simple beaker-type undivided cell under a constant current condition to afford the corresponding ketones, aldehydes, and/or carboxylic acid in moderate to good yields. Recycle use of both the PBZT_NT-N-Oxyl particles and the aqueous media could be achieved successfully by immobilization of additional N-oxyl moiety on the polymer particles in an appropriate interval. Notably, the shape and the particle size of PBZT_NT-N-Oxyl were not appreciably changed even after 60 times recycle use.     

Electron-transfer mechanism in radical-scavenging reactions by a vitamin E model in a protic medium

The scavenging reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) or galvinoxyl radical (GO.) by a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), was significantly accelerated by the presence of Mg(ClO4)2 in de-aerated methanol (MeOH). Such an acceleration indicates that the radical-scavenging reaction of 1H in MeOH proceeds via an electron transfer from 1H to the radical, followed by a proton transfer, rather than the one-step hydrogen atom transfer which has been observed in acetonitrile (MeCN). A significant negative shift of the one-electron oxidation potential of 1H in MeOH (0.63 V vs. SCE), due to strong solvation as compared to that in MeCN (0.97 V vs. SCE), may result in change of the radical-scavenging mechanisms between protic and aprotic media.     

Stereochemical control in yeast reduction

A substrate which is subjected to yeast reduction has been modified by iodination or phenylsulfonylation. Both substituents improves chemical and optical yields and control the stereochemical course of the reduction.     

Circular dichroism of hydrolysable tannins-I ellagitannins and gallotannins

The Cotton effects around 235, 265 and 285 nm in the CD spectra of twenty hydrolysable tannins and related compounds were empirically correlated with the stereostructures of ellagitannins and gallotannins.     

Circular dichroism of hydrolysable tannins-II dehydroellagitannins

The CD spectra of dehydroellagitannins and related compounds have empirically shown that the absolute configuration at C-1′ of the dehydrohexahydroxydiphenoyl group can be determined by the Cotton effect around 200 nm.     

On the reaction mechanism of gamma-ray solid-state copolymerization

The gamma-ray induced solid-state polymerization of binary mixtures consisting of a maleimide derivative as the first component and acenaphthylene or trans-stilbene as the second component was investigated regarding the occurrence of copolymerization. The binary solid mixture of these compounds exhibited a phase-equilibrium diagram including a simple eutectic mixture, and the irradiation caused the formation of a random copolymer together with that of homopolymers of component comonomers. The reaction rates and the composition of products suggested that the mobility of monomer molecules in the crystals affected the solid-state polymerization significantly. The solid-state copolymerization was supposed to take place by the diffusion of comonomer molecules via a vapor phase to the nuclei where the copolymerization proceeded.     

Effect of substituents on the thermal decomposition of diazirines: experimental and computational studies

The thermal decomposition of phenylchlorodiazirine (1), phenyl-n-butyldiazirine (2), and 2-adamantane-2,3'-[3H]diazirine (3) has been studied in solution in the presence of C(60). The C(60) probe technique indicates that in the decomposition diazirine 1 yielded exclusively phenylchlorocarbene, diazirine 2 yielded mainly a diazo intermediate, and diazirine 3 yielded a mixture of carbene and diazo compound. In the case of diazirine 2, 13% of (E)-1-phenyl-1-pentene resulted from the direct thermal rearrangement of diazirine without the participation of a carbene. As well, the thermal decomposition of these diazirines has been studied theoretically with ab initio and density functional methods. The experimental results are broadly in agreement with the theoretical predictions. The calculations further indicate that the rebound reaction between carbene and molecular nitrogen leading to the formation of a diazo intermediate is an important reaction in the gas-phase decomposition of diazirine.     

A convenient synthesis and antifungal activity of 1-aryl-1H- and 1-aryl-3-heteroaryl-1H-pyrazolo[3,4-b]quinoxalinesA Convenient Synthesis and Antifungal Activity

Novel 1-aryl-1H- and 1-aryl-3-heteroaryl-1H-pyrazolo[3,4-b]quinoxalines (flavazoles) 9a-c, 12, 13 were synthesized from 3-methyl-2-oxo-1,2-dihydroquinoxaline 5 and the 3-triazolylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline 6, respectively, via a facile hydrazone synthesis using aryl diazonium salts. Some of the above flavazoles and their related compounds exhibited the antifungal activity in some extent. The above results are described.