InCl3/I2-catalyzed cross-coupling of alkyl trimethylsilyl ethers and allylsilanes via an in situ derived combined Lewis acid of InCl3 and Me3SiI

Direct Csp3-Csp3 coupling of various aliphatic trimethylsilyl ethers and allylsilanes is effectively catalyzed by InCl3 and I2. The transformation is thought to involve an in situ-derived combined Lewis acid of InCl3 and Me3SiI. The reaction can be used for the construction of quaternary-quaternary and quaternary-tertiary carbon-carbon bonds. This system enabled a highly chemoselective coupling to be conducted with a trimethylsilyl ether including an aryl halide moiety. Furthermore, couplings were possible using an alkynyltrimethylsilane and a trimethylsilyl ketene acetal.     

Distance determination in human ubiquitin by pulsed double electron-electron resonance and double quantum coherence ESR methods

Recently, distance measurements by pulsed ESR (electron spin resonance) have been obtained using pulsed DEER (double electron-electron resonance) and DQC (double quantum coherence) in SDSL (site directed spin labeling) proteins. These methods can observe long range dipole interactions (15-80A). We applied these methods to human ubiquitin proteins. The distance between the 20th and the 35th cysteine was estimated in doubly spin labeled human ubiquitin. Pulsed DEER requires two microwave sources. However, a phase cycle is not usually required in this method. On the other hand, DQC-ESR at X-band ( approximately 9GHz) can acquire a large echo signal by using pulses of short duration and high power, but this method has an ESEEM (electron spin echo envelope modulation) problem. We used a commercial pulsed ESR spectrometer and compared these two methods.     

Quantum mechanical energy-based screening of combinatorially generated library of tautomers. TauTGen: a tautomer generator program

We describe a procedure of finding low-energy tautomers of a molecule. The procedure consists of (i) combinatorial generation of a library of tautomers, (ii) screening based on the results of geometry optimization of initial structures performed at the density functional level of theory, and (iii) final refinement of geometry for the top hits at the second-order M?ller-Plesset level of theory followed by single-point energy calculations at the coupled cluster level of theory with single, double, and perturbative triple excitations. The library of initial structures of various tautomers is generated with TauTGen, a tautomer generator program. The procedure proved to be successful for these molecular systems for which common chemical knowledge had not been sufficient to predict the most stable structures.     

Indium Tribromide Catalyzed Coupling Reaction of Enol Ethers with Silyl Ketene Imines toward the Synthesis of β,γ‐Unsaturated Nitriles

Herein, a coupling reaction of enol ethers with silyl ketene imines in the presence of catalytic amounts of InBr₃ and Me₃SiBr is described. Kinetic studies have revealed that an indium catalyst and Me₃SiBr accelerated the coupling process and the regeneration of the catalyst, respectively. Various types of enol ethers and silyl ketene imines are applicable. In addition, a formal synthesis of verapamil was achieved by using this novel coupling reaction.     

Improved high-performance liquid chromatographic method for the determination of apolipoproteins in serum high-density lipoproteins

Ofloxacin, fenbufen and its active metabolite, felbinac, were simultaneously extracted from 50 microliters of rat plasma and analysed by high-performance liquid chromatography on a reversed-phase column. Quantitative and reproducible determinations were possible for ofloxacin, fenbufen and felbinac over the concentration ranges 0.15-40, 0.3-80 and 0.45-45 micrograms/ml, respectively. The detection limits for all the drugs were lower than those reported previously. The recovery of ofloxacin, fenbufen and felbinac added to plasma was nearly 100% with a coefficient of variation of less than 3.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of ofloxacin and fenbufen.     

Fluorimetric determination of oleandomycins with nicotinamide and 3-acetylpyridine

The method is based on a fluorescence reaction of the epoxy group with nicotinamide and 3-acetylpyridine. Oleandomycin phosphate and triacetyloleandomycin can be determined in the ranges 1–80 μg ml^?1and 5–80 μg ml^?1, respectively, with relative standard deviations of 3–5%. The method can be applied to pharmaceutical preparations. Results obtained by this method and by bioassay in an examination of residual potency agreed well when degradation was done under neutral or alkaline conditions.     

Amperometric determination of phosphatidyl choline in serum with use of immobilized phospholipase d and choline oxidase

Phospholipase D (EC 3.1.4.4.) and choline oxidase (EC 1.1.99.1.) are immobilized together on a hydrophobic agarose gel and used to convert the phospholipid to betaine and hydrogen peroxide, which is measured amperometrically at + 0.60 V vs. SCE. The response time of the sensor is 2 min, and the calibration curve for 0–3 g l^-1 of phosphatidyl choline is linear. Different methods of insolubilizing the enzymes are compared.     

Improvement in the quality of hematopoietic prostaglandin D synthase crystals in a microgravity environment

Human hematopoietic prostaglandin synthase, one of the better therapeutic target enzymes for allergy and inflammation, was crystallized with 22 inhibitors and in three inhibitor-free conditions in microgravity. Most of the space-grown crystals showed better X-ray diffraction patterns than the terrestrially grown ones, indicating the advantage of a microgravity environment on protein crystallization, especially in the case of this protein.