A practical synthetic method for vinyl chlorides and vinyl bromides from ketones via the corresponding vinyl phosphate intermediates

A new synthetic method for the preparation of vinyl chlorides and vinyl bromides from acyclic and cyclic ketones is described. Vinyl halides are practically obtained from the corresponding vinyl phosphate intermediates with triphenylphosphine dihalide.     

Drying dissipative structures of thermo-sensitive gel spheres of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide)

Drying dissipative patterns were observed at 25 °C, 33 °C, and 45 °C on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of colloidal crystals of the thermo-sensitive gels of poly(N-isopropylacrylamide) (PNIPA). Two kinds of broad rings, i.e., transparent ring at the outside edge and the ring in the inner area from the edge, were observed. Sizes of the former were the same as those of the initial liquids irrespective of gel concentration, whereas sizes of the latter decreased as gel concentration decreased. These broad rings were composed mainly of the monomeric and the agglomerated gel particles, respectively. Formation of the monodispersed agglomerated particles and their ordered arrays in the inner area of the dried film were observed especially on a Petri glass dish and a watch glass. The important role of the electrical double layers formed around the agglomerated particles is supported for the ordering of the agglomerated particles. The essential differences in the drying patterns between PNIPA gel spheres and the typical colloidal particles did not appear.     

Improved lateral-flow immunoassays for chlamydia and immunoglobulin M by sequential rehydration of two-phase system components within a paper-based diagnostic

Microchimica Acta - Frequent screening of at-risk individuals using paper-based point-of-care diagnostics is a promising method for attenuating the spread of chlamydia and HIV. However, such...     

Sequence-selective osmium oxidation of DNA: efficient distinction between 5-methylcytosine and cytosine

5-Methylcytosine was distinguished from cytosine using the large difference of their osmium oxidation rates, and this reaction was applied to detection of the cytosine methylation status at a specific site of a long sequence using the formation of a bulge structure by hybridization with a guide DNA.     

Control of diastereoselectivity in the crotylation and cinnamylation of aldehydes by the selection of ligands on allylic indium reagents

Diastereoselective couplings of salicylaldehyde, anisaldehyde and 2-pyridylaldehyde with crotyl- and cinnamylindium reagents were studied. The syl/anti selectivity was found to depend largely on the ligands on the indium atom of the allylic indium reagents. A syn-selective cinnamylation of salicylaldehyde was realized by the combination of cinnamyl acetate and indium(I) iodide, whereas an anti-selective coupling with salicylaldehyde was achieved by the indium trichloride/aluminium-mediated cinnamylation.     

Comprehensive analysis system using liquid chromatography-mass spectrometry for the biosynthetic study of peptides produced by cyanobacteria

Microcystins are hepatotoxic heptapeptides and general tumor promoters produced by several species of the genera Microcystis, Anabaena, Oscillatoria and Nostoc. They are non-ribosomally synthesized via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. We have carried out the detection, isolation and structural determination of non-toxic peptides produced together with microcystins by toxic cyanobacteria, which are classified into several groups on the basis of their structures and some of these non-toxic peptides are also non-ribosomally synthesized as well as microcystins. In the present study, we tried to correlate the secondary metabolic peptides produced by the hepatotoxic cyanobacteria with the corresponding peptide synthetase genes. An analytical method using LC-electroscopy ionization MS and photodiode array detection was developed for the exhaustive screening of cyanobacterial peptides in Japanese strains and it was successfully applied to the peptide fractions extracted from these strains. The established method was advantageous over conventional ones using the usual HPLC and matrix-assisted laser desorption ionization time-of-flight MS, because more structural information could be obtained and it is easier to distinguish microcystins from other peptides using this method. Small amounts of other peptides could also be detected by this method. The established method will contribute to the investigation of the relationship between genes encoding the peptide synthetase and secondary metabolic peptides.     

Production of theasinensins A and D, epigallocatechin gallate dimers of black tea, by oxidation-reduction dismutation of dehydrotheasinensin A

Theasinensins A and D are B,B′-linked dimers of (−)-epigallocatechin 3-O-gallate connected through R and S biphenyl bonds, respectively, and are major constituents of black tea. Enzymatic oxidation of epigallocatechin 3-O-gallate produced dehydrotheasinensin A, and the structure was shown to be equivalent to an o-quinone of theasinensin A. When the aqueous solution of dehydrotheasinensin A was heated, theasinensin D was produced along with galloyl oolongtheanin. On the other hand, dehydrotheasinensin A was converted to theasinensins A and D along with oxidation products in phosphate buffer at pH 6.8 at room temperature. The results strongly suggested that theasinensins in black tea were produced by oxidation-reduction dismutation of dehydrotheasinensin.     

Preparation and characterization of two crystalline forms of 4-amino-5-chloro-2-methoxy-N-[(2S,4S)-1-ethyl-2-hydroxymethyl-4-pyrroli dinyl]benzamide (TKS159)

For 4-amino-5-chloro-2-methoxy-N-[(2S,4S)-1-ethyl-2-hydroxymethyl-4-pyrrolid inyl]benzamide (TKS159), two polymorphs, forms alpha and beta, were prepared and characterized by means of X-ray powder diffractometry, thermal analysis, infrared spectroscopy and 13C-NMR spectroscopy, both in the solution and solid phases. The X-ray powder diffraction analysis gave different patterns for forms alpha and beta. In the thermogravimetry and differential thermal analysis profiles, form beta exhibited characteristic endo- and exothermic peaks at 112.7 degrees C and 116.2 degrees C, respectively, due to the partial melting-induced phase transition to form alpha without accompanying weight loss, and these were followed by an additional endothermic peak at 138.2 degrees C due to fusion. For form alpha, only an endothermic peak at 137.8 degrees C due to fusion was observed. The IR spectroscopic analyses of forms alpha and beta gave different absorption bands assigned to N-H and O-H stretching, N-H bending, and C=O stretching vibrations. From the data obtained by thermal analysis, form alpha was shown to be thermodynamically more stable than form beta.