Entropy production and nonequilibrium stationarity in quantum dynamical systems. Physical meaning of van Hove limit

With aid of the so-called dilation method, a concise formula is obtained for the entropy production in the algebraic formulation of quantum dynamical systems. In this framework, the initial ergodic state of an external force system plays a pivotal role in generating dissipativity as a conditional expectation. The physical meaning of van Hove limit is clarified through the scale-changing transformation to control transitions between microscopic and macroscopic levels. It plays a crucial role in realizing the macroscopic stationarity in the presence of microscopic fluctuations as well as in the transition from non-Markovian (groupoid) dynamics to Markovian dissipative processes of state changes. The extension of the formalism to cases with spatial and internal inhomogeneity is indicated in the light of the groupoid dynamical systems and noncommutative integration theory.     

Acceleration effect of an allylic hydroxy group on ring-closing enyne metathesis of terminal alkynes: scope, application, and mechanistic insights

An interesting acceleration effect of an allylic hydroxy group on ring-closing enyne metathesis has been found. Ring-closing enyne metathesis of terminal alkynes possessing an allylic hydroxy group proceeded smoothly without the ethylene atmosphere generally necessary to promote the reaction. The synthesis of (+)-isofagomine with the aid of this efficient reaction has been demonstrated. Mechanistic studies of the acceleration effect were also carried out. Results of NMR studies suggested that the reaction proceeded via an "ene-then-yne" pathway. Kinetic studies indicated switching of the rate-determining step as a consequence of the presence of an allylic hydroxy group. These results suggest acceleration of the reentry step of Ru-carbene species by the allylic hydroxy group.     

New and direct route to 5-trifluoromethyl-5,6-dihydrouracils by means of palladium complex catalyzed “ureidocarbonylation” of 2-bromo-3,3,3-trifluoropropene

Palladium complex catalyzed carbonylation of 2-bromo-3,3,3-trifluoropropene (2-Br-TFP) with ureas afforded 5-trifluoromethyl-5,6-dihydrouracils in moderate to good yields, which were converted into 5-trifluoromethyluracils in nearly quantitative yields.     

Solute partition study in aqueous sodium dodecyl sulfate micellar solutions for some organic reagents and metal chelates

The partition constants (K _d) have been estimated for nitrophenols, thiazolylazo dyestuffs and metal chelate compounds into the sodium dodecyl sulfate (SDS) micellar phase at an ionic strength of 0.10M [(H⁺, Na⁺)Cl^–] and at 20 °C. The equilibrium partition data obtained by batch-wise solution spectrophotometry (equilibrium shift method) agree well with those by the micellar electrokinetic capillary chromatography (MECC) with the SDS micellar pseudo-stationary phase. The MECC clearly discriminates a very small difference (0.03) in the logK _d values of some metal chelates. The plot of theK _d values with the van der Waals volume of the solute molecules obviously shows the leveling-off of theK _d values over solute size near 110 ml/mol, which seems to be consistent with the results obtained in the Triton X-100 micellar system. This phenomenon arises most probably from the rigidity of the micellar pseudo-phase (a micellar volume-constraint effect) in sharp contrast with true two-phase partitioning such as solvent extraction systems.     

Reduction of carbonyl compounds via hydrosilylation : I. Hydrosilylation of carbonyl compounds catalyzed by tris(triphenylphosphine)chlororhodium

The hydrosilylation of various carbonyl compounds such as simple aldehydes, simple ketones, α,β-unsaturated carbonyl compounds, α-diketones, acyl cyanides and ketones having an electron-withdrawing group on the α-carbon using tris(triphenylphosphine)chlororhodium as a catalyst is described. Solvolysis of these silyl ethers and silyl enol ethers afforded the corresponding reduced products. The hydrosilylation of α,β-unsaturated carbonyl compounds was found to proceed by 1,4-addition. An oxidative adduct of triethylsilane to the rhodium-(I) complex was obtained as a reaction intermediate. The structure of the adduct was discussed on the basis of its IR and far-IR spectra.     

Chemistry and chemical biology of taxane anticancer agents

Taxol (paclitaxel) and Taxotere (docetaxel) are currently considered to be among the most important anticancer drugs in cancer chemotherapy. The anticancer activity of these drugs is ascribed to their unique mechanism of action, i.e., causing mitotic arrest in cancer cells, leading to apoptosis through inhibition of the depolymerization of microtubules. Although both paclitaxel and docetaxel possess potent antitumor activity, treatment with these drugs often results in a number of undesirable side effects, as well as multidrug resistance (MDR). Therefore, it has become essential to develop new anticancer agents with superior pharmacological properties, improved activity against various classes of tumors, and fewer side effects. This paper describes an account of our research on the chemistry of paclitaxel and taxoid anticancer agents at the biomedical interface, including: 1. The structure-activity relationship (SAR) study of taxoids leading to the development of the "second-generation" taxoids, which possess exceptional activity against drug-resistant cancer cells expressing the MDR phenotype. 2. Development of fluorinated taxoids to study the bioactive conformation of paclitaxel and photoaffinity labeling taxoids for mapping of the drug-binding domain on both microtubules and P-glycoprotein. 3. The synthesis of novel macrocyclic taxoids for the investigation into the common pharmacophore for microtubule stabilizing anticancer agents.     

Binuclear Copper(II) Complexes in which other copper(II) complexes are coordinated as bidentate ligands

Twelve new copper(II) complexes in which N,N′-bis-(2-pyridylmethyl)-oxamidatocopper(II) or N,N′-bis(2-pyridylethyl)-oxamidatocopper(II) coordinates as a bidentate ligand have been isolated and characterized. These complexes have a structure bridged by the oxamide group (including two tetranuclear complexes formed by olation of two binuclear complexes, of. Fig. 1), and possess Cu? Cu interaction resulting in a sub-normal magnetic moment at room temperature. In one of them, [Cu₂(PMoxd) (bipy)₂] (NO₃)₂ (cf. Fig. 2), each copper(II) ion has a five-coordinated environment.     

Binuclear Copper(II) Complexes. N,N′-bis(3-aminopropyl)-oxamidatocopper(II) coordinated as a bidentate ligand

Four new binuclear copper(II) complexes having sub-normal magnetic moment have been synthesized by reaction of N, N′-bis(3-aminopropyl)-oxamidatocopper(II) with another copper(II) compound such as mono- and bis-(2,2′-bipyridine)-copper(II) nitrate, cupric mono-malonate, or cupric chloride. One of them, [Cu₂(APxd)(bipy)₂](NO₃)₂(cf. Fig. 2), was recognized to be a binuclear complex in which each copper(II) ion has a five-coordinated environment. The data from analyses, IR and electronic spectra, magnetic susceptibility measurements, and conductivity measurements were used to establish the structures.     

Syntheses and characterization of μ-Bis{N-(oxopropyl)-glycinamidato}-dicopper(II) and μ-Bis{n-(oxopropyl)-DL-alaninamidato}-dicopper(II)

Two new complexes, [Cu(OP-gld)]₂ and [Cu(OP-alad)]₂ (shown in Fig. 2) with a subnormal magnetic moment have been synthesized and characterized by means of analyses, magnetic susceptibility measurements, IR-, and electronic spectra, and conductivity measurement.