One-pot oxidative Mannich-type reaction of lactams with alkyl malonates

One-pot substitution of a C-H bond at the position next to the nitrogen atom of lactams with alkyl malonates proceeded effectively by dehydrogenation of lactams with N-tert-butylbenzenesulfinimidoyl chloride, followed by Mannich-type addition of alkyl malonates.     

Derivatization of neutral steroids to enhance their detection characteristics in liquid chromatography–mass spectrometry

This review article underlines the detection-oriented derivatization of neutral steroids in liquid chromatography-mass spectrometry (LC-MS). Steroids have strong biological activity at very low concentrations in target tissues and, therefore, the analysis of steroids in body fluids or tissues is necessary to elucidate the nature of the many endocrine disease processes and thus be useful for diagnosis and treatment. LC-MS has recently been used for steroid analysis because of its specificity and versatility, but the ionization efficiencies of most steroids are relatively low for the different ionization methods. Derivatization enhances the ionization efficiencies of steroids, leading to high sensitivity and specific detection. For electrospray ionization MS the introduction of permanently charged moieties or easily ionizable moieties effectively increases the sensitivity of detection of steroids. The introduction of moieties with proton affinity or electron affinity enhances the analyte signals in positive and negative atmospheric pressure chemical ionization MS, respectively.     

Mononuclear nonheme ferric-peroxo complex in aldehyde deformylation

A mononuclear nonheme ferric-peroxo complex bearing a macrocyclic tetradentate N4 ligand, [(TMC)Fe(III)-O2]+, was prepared and used in mechanistic studies of aldehyde deformylation; a catalytic aldehyde deformylation by a nonheme iron(II) complex, [Fe(II)(TMC)]2+, and molecular oxygen is reported as well.     

Effects of metal salts on polymerization. Part VII. Radical polymerization and spectra of vinylpyridine in the presence of cobaltous chloride

The radical polymerizability of vinylpyridines in the presence of cobaltous chloride was studied in DMF solution, and the results were correlated with the spectroscopic data obtained for methanol solution. In general, the behavior of vinylpyridine complexed with cobaltous chloride is qualitatively the same as that of zinc complexes reported previously. The rates of polymerization were enhanced by the addition of cobaltous chloride when 4-vinylpyridine(4-VP) or 2-methyl-5-vinylpyridine(MVP) was the monomer, whereas the polymerization of 2-vinylpyridine(2-VP) was retarded by cobaltous chloride. The monomer reactivity of all the vinylpyridines was also enhanced by complex formation as studied by copolymerization with styrene. The enhancement of reactivity of 4-VP complexed with cobaltous chloride is somewhat smaller than that of the corresponding zinc complex.     

Conformation of hedycaryol isomers

Ground state conformation for all possible geometrical isomers of hedycaryol was estimated by the molecular mechanics calculations. All isomers are indicated to exist in more than two conformations and the parallel conformation (TC or TT) is most stable for all isomers.     

Effects of adrenergic blockers or bicuculline on diazepam induced changes in rat pineal melatonin synthesis in vivo and in vitro.

The effect of propranolol (PPL), phenoxybenzamine (PBZ) or bicuculline (BCL) on the diazepam (DZP)-induced changes of pineal melatonin synthesis in male rats was examined in vivo and in vitro. Administration of PBZ did not affect the inhibitory action of DZP on pineal melatonin synthesis in vivo. A single injection of PPL inhibited the pineal melatonin synthesis similarly to the administration of DZP alone, but the two drugs together did not exhibit additive or synergistic effects on the melatonin synthesis. Significant decreases in the N-acetyltransferase (NAT) activity and the N-acetylserotonin (NAS) and melatonin contents were observed in the BCL-injected group, being greater than those in the DZP-treated group. Unexpectedly, however, the combination treatment of DZP and BCL causes an increase in the NAT activity and melatonin content compared with the BCL-alone group. Incubation with DZP at higher concentrations resulted in an increase of pineal NAT activity in vitro, but this increase was inhibited by preincubation with PPL, PBZ or BCL. DZP treatment thus appeared to have different effects on pineal NAT activity in vivo and in vitro. These results suggest that both a GABAergic mechanism and peripheral benzodiazepine (BZP) receptors in rat pineal gland may be involved in the modulation of melatonin synthesis by DZP.     

Mechanism of the CO oxidation reaction on O-precovered Pt(111) surfaces studied with near-edge x-ray absorption fine structure spectroscopy

The mechanism of CO oxidation reaction on oxygen-precovered Pt(111) surfaces has been studied by using time-resolved near-edge x-ray absorption fine structure spectroscopy. The whole reaction process is composed of two distinct paths: (1) a reaction of isolated oxygen atoms with adsorbed CO, and (2) a reaction of island-periphery oxygen atoms after the CO saturation. CO coadsorption plays a role to induce the dynamic change in spatial distribution of O atoms, which switches over the two reaction paths. These mechanisms were confirmed by kinetic Monte Carlo simulations. The effect of coadsorbed water in the reaction mechanism was also examined.     

Kinetic study of the electron-transfer oxidation of the phenolate anion of a vitamin E model by molecular oxygen generating superoxide anion in an aprotic medium

Electron-transfer reduction of molecular oxygen (O2) by the phenolate anion (1-) of a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), occurred to produce superoxide anion, which could be directly detected by a low-temperature EPR measurement. The rate of electron transfer from 1- to O2 was relatively slow, since this process is energetically unfavourable. The one-electron oxidation potential of 1- determined by cyclic voltammetric measurements is sufficiently negative to reduce 2,2-bis(4-tert-octylphenyl)-1-picrylhydrazyl radical (DOPPH*) to the corresponding one-electron reduced anion, DOPPH-, suggesting that 1- can also act as an efficient radical scavenger.     

Retention behavior of bile acid derivatives using cyclodextrin in the mobile phase in high-performance liquid chromatography

The retention behavior of 3-(1-anthroyl)bile acids together with bile acid glucuronides, sulfates, and 12-dehydro derivatives is examined by the addition of cyclodextrin to the mobile phase in reversed-phase high-performance liquid chromatography. The data suggest that the functional group at the 12 position of the steroid moiety may be the important factor for the formation of the inclusion complex from the solute and cyclodextrin. The separation of these bile acid derivatives is much improved by this inclusion chromatography.