SmI2-induced reductive cyclization of optically active β-alkoxyvinyl sulfoxides with aldehyde

SmI₂-induced reductive cyclization of optically active (E)- and (Z)-β-alkoxyvinyl sulfoxides with aldehyde was developed for the construction of several stereoisomers of tetrahydropyran derivatives.     

A practical procedure for the synthesis of multifunctional aldehydes through the Fukuyama reduction and elucidation of the reaction site and mechanism

A highly efficient heterogeneous Pd/C catalyst D1 was found to effect the reduction of thiol esters 1 to the corresponding aldehydes 2 with such a low catalyst loading as 0.5-1.0 mol %. The chemical properties of the Pd/C catalysts together with the XRF analysis reveal that the reduction is most likely to proceed on the solid surface of the Pd/C catalyst rather than in the solution phase outside the pores. A reaction mechanism through oxidative addition of Pd to the thiol esters 1 was postulated by detection of the oxidative addition intermediate by React IR analysis. A practical purification of 2 was accomplished by conversion to water-soluble bisulfite adducts 7.     

Asymmetric [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene

The reaction of (E)-1-(phenylseleno)-2-(trimethylsilyl)ethene (1) and vinyl ketones 2a-d in the presence of a chiral Lewis acid prepared from TiCl(4), Ti(O(i)Pr)(4), (R)- or (S)-1,1'-binaphthol (BINOL), and MS4A gave enantiomerically enriched cis cyclopropane products 3a-d. The enantiomeric excess and chemical yield varied depending on the ratio of TiCl(4) and Ti(O(i)Pr)(4) to 1. Reproducible results (43-47% ee/33-41% yields) for cis-1-acetyl-2-[(phenylseleno)(trimethylsilyl)methyl]cyclopropane (3a) were obtained using 1.1 equiv of TiCl(4), 0.54-0.65 equiv of Ti(O(i)Pr)(4), and 1.65 equiv of BINOL. The observed enantioselectivity was explained by consideration of the structure of the postulated intermediates, alkoxy titanium-carbonyl complexes, via ab initio MO calculations.     

Diels-alder reaction of (E)-4-(2-nitroethenyl)-1H-imidazoles and methyl (E)-3-(1-imidazol-4-yl)propenoates

Diels-Alder reaction of methyl (E)-3-(1H-imidazol-4-yl)propenoates 2, 3a-c and (E)4-(2-nitroethenyl)-1H-imidazoles 3d,e with 2,3-dimethyl-1,3-butadiene, cyclopentadiene, and cyclohexa-1,3-diene gave the corresponding cycloadducts 6–9 .     

Reliable and fast allele-specific extension of 3'-LNA modified oligonucleotides covalently immobilized on a plastic base, combined with biotin-dUTP mediated optical detection.

In the present work, a convenient microarray SNP typing system has been developed using a plastic base that covalently immobilizes amino-modified oligonucleotides. Reliable SNP allele discrimination was achieved by using allelic specificity-enhanced enzymatic extension of immobilized oligonucleotide primer, with a locked nucleic acid (LNA) modification at the SNP-discriminating 3'-end nucleotide. Incorporation of multiple biotin-dUTP molecules during primer extension, followed by binding of alkaline phosphatase-conjugated streptavidin, allowed optical detection of the genotyping results through precipitation of colored alkaline phosphatase substrates onto the surface of the plastic base. Notably, rapid primer extension was demonstrated without a preliminary annealing step of double-stranded template DNA, allowing overall processes to be performed within a couple of hours. Simultaneous evaluation of three SNPs in the genes TGFB1, SOD2 and APEX1, previously investigated for association with radiation sensitivity, in 25 individuals has shown perfect assignment with data obtained by another established technique (MassARRAY system).     

Development of recyclable iridium catalyst for C-H borylation

Aromatic C-H borylation using [IrCl(COD)]₂ and 2,2′-bipyridinedicarboxylic acids was studied. 2,2′-Bipyridine-4,4′-dicarboxylic acid was complexed with [IrCl(COD)]₂ in the presence of bis(pinacolato)diboron. The resulting iridium catalyst could be readily separated from the reaction mixture by simple filtration, and the recovered catalyst under a nitrogen atmosphere was still active and could be reused more than 10 times.     

An improved method for proteomics studies in C. elegans by fluorogenic derivatization, HPLC isolation, enzymatic digestion and liquid chromatography--tandem mass spectrometric identification

An improved method for proteomics studies, which includes the fluorogenic derivertization of protein mixtures with 7-chloro-4-(dimethylaminoethylaminosulfonyl)-2,1,3-benzoxadiazole (DAABD-Cl), followed by HPLC isolation, enzymatic digestion and identification of the derivatized proteins by HPLC-electrospray ionization (ESI)-MS/MS with the probability-based protein identification algorithm, identified 103 proteins in the soluble extract (10 microg protein) of Caenorhabditis elegans.     

Thermal behavior of polystyrene synthesized in the presence of carboxymethyl cellulose

Summary Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, parameters such as activation energy, frequency factor and reaction order, were measured under dynamic conditions. Flynn-Wall-Ozawa, Van Krevelen, Horowitz-Metzger, Coats-Redfern, Madhusudanan and Vyazovkin methods were used to determine the kinetic parameters. The analysis of the results obtained by the Coats-Redfern method shows that the thermal degradation process of LDPE and HDPE corresponds to a phase boundary controlled reaction (mechanism R2). This method shows that the reaction order values of LDPE and HDPE are about 0.7 and 0.6, respectively.     

Observation of an Fe(II) spin-crossover in a cesium iron hexacyanochromate

In this work, we observed a spin-crossover phenomenon in a cesium iron hexacyanochromate, which is a Prussian blue analogue. This compound showed a thermal phase transition with transition temperatures of 211 K (T1/2 downward arrow) and 238 K (T1/2 upward arrow) due to a spin-crossover on FeII sites. This spin-crossover phase transition is accompanied by a lattice contraction of 0.38 A, but maintains a face-centered cubic structure (F3m). This is the first observation of FeII spin-crossover in a series of Prussian blue analogues.