Phase-vanishing reactions that use fluorous media as a phase screen. Facile,controlled bromination of alkenes by dibromine and dealkylation of aromatic ethers by boron tribromide

In fluorous triphasic reactions, such as bromination of alkenes by dibromine and dealkylation of aromatic ethers by boron tribromide, the middle fluorous phase acts as a liquid membrane permitting passive transport of the reagents at the bottom to the top layer involving the substrates, thereby regulating the reactions.     

Non-covalent switch for intramolecular energy transfer

The axially coordinated complex of phenylazopyridine and a Zn-porphyrin/free-base porphyrin conjugate provides a switch for intramolecular energy transfer, with reversible complexation/decomplexation as a switching protocol.     

Synthesis of 2-decenedioic acid (royal jelly acid) by sequential carbonylation of butadiene catalyzed by a palladium—phosphine complex and dicobalt octacarbonyl

Carbonylation of butadiene in t-butyl alcohol catalyzed by a palladium complex gave t-butyl-3,8-nonadienoate (I). Further carbonylation of I in methanol with Co₂(CO)₈ afforded t-butylmethyl-3-decenedioate (II) as the main product. Hydrolysis and base-catalyzed isomerization of II produced E-2-decenedioic acid.     

Structure of nm-sized InSb clusters formed by spontaneous alloying

The negative ion photoelectron spectrum of⁷Li ₂ ^– is reported at 488 nm (2.540 eV). Three electronic bands are observed in this spectrum and are assigned to the following photodetachment transitions:⁷Li₂,X ¹ _g ⁺ +e ^{– 7}Li ₂ ^– ,X ² _u ⁺ ;⁷Li₂,a ³ _u ⁺ +e ^{– 7}Li ₂ ^– ,X ² _u ⁺ ; and⁷Li₂,A ¹ _u ⁺ +e ^{– 7}Li ₂ ^– ,X ² _u ⁺ . The electron affinity of⁷Li₂ is determined to be 0.437±0.009 eV, leading to an anion dissociation energy,D ₀, of 0.865±0.022 eV for the ground state of⁷Li ₂ ^– . A Franck-Condon analysis of the⁷Li₂,X ¹ _g ⁺ +e ^{– 7}Li ₂ ^– ,X ² _u ⁺ band yields the following spectroscopic constants for the ground state of⁷Li ₂ ^– :B _e =0.502±0.005 cm^–1,r _e =3.094±0.015 Å, and _e =232±35 cm^–1.     

Methods for the synthesis of 5,6,7,8-tetrahydro-1,8-naphthyridine fragments for alphaVbeta3 integrin antagonists

The preparation of 3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propan-1-amine 2a and 3-[(7R)-7-methyl-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl]propan-1-amine 2b, key intermediates in the synthesis of alpha(V)beta(3) antagonists, is described. The syntheses rely on the efficient double Sonogashira reactions of 2,5-dibromopyridine 3 with acetylenic alcohols 4a/4b and protected propargylamines 10a-e followed by Chichibabin cyclizations of 3,3'-pyridine-2,5-diyldipropan-1-amines 9a/9b.     

Solvent‐induced reversible color changes in block copolymer films and new locking method of structural colors

The well‐defined polystyrene‐block‐poly(4‐vinylpyridine) [PS‐block‐P4VP (SV1); lamellar morphology] and polyisoprene‐block‐poly(α‐methyl styrene) [PI‐block‐PMS (IMS1); PI spherical morphology] diblock copolymers were prepared by sequential anionic polymerization techniques. The segregated chains in the P4VP lamellar layers of the SV1 film (PS lamellae: 41 nm; P4VP lamellae: 51 nm) were crosslinked with 1,4‐dibromobutane. This crosslinked film was insoluble in organic solvents such as benzene and chloroform (CHCl₃) and exhibited various structural colors under the swollen state. The IMS1 film (body‐centered cubic lattice, diameter of PI spheres: 53 nm) was soaked in the mixture of CHCl₃/hexane (1 : 10, v/v). This solvent system resulted in the swelling of PI spherical domains. The transmitted and reflected light color through the swollen film changed to a deep blue. Such color changes were reversible upon swelling in solvent and evaporation of the solvent. Subsequently, photofunctional diethyldithiocarbamate (DC) groups were introduced into the PS block of the parent block copolymer IMS1 by means of polymer reactions. The locking of the cubic lattice was performed with living radical graft copolymerization from DC groups of swollen as‐cast film in methyl methacrylate (MMA) under UV irradiation. The locking of structural colors such as blue and green was also achieved, varying the content of poly(methyl methacrylate) (PMMA) grafted chains. Copyright © 2005 John Wiley & Sons, Ltd.     

Microbial synthesis and characterization of polyhydroxyalkanoates with fluorinated phenoxy side groups from Pseudomonas putida

Microbial poly(3-hydroxyalkanoates) (PHAs) with fluorinated phenoxy side groups were produced by Pseudomonas putida when fluorophenoxyalkanoic acids were used as carbon sources. 11-(2-Fluorophenoxy)undecanoic acid (2FPUDA), 11-(3-fluorophenoxy)undecanoic acid (3FPUDA), 11-(4-fluorophenoxy)undecanoic acid (4FPUDA), 11-(2,4-difluorophenoxy)undecanoic acid (2,4DFPUDA), 11-(2,4,6-trifluorophenoxy)undecanoic acid (2,4,6TFPUDA), and 11-(2,3,4,5,6-pentaflurophenoxy)undecanoic acid (2,3,4,5,6PFPUDA) were used as carbon sources in the present study. When cells were grown with 2,4DFPUDA, the production of homo poly(3-hydroxy-5-(2,4-difluorophenoxy)pentanoate) was confirmed by NMR and GC/MS analyses. Fluorine atoms inserted into the side chain of the PHA dramatically affected its physical properties. In marked contrast to medium chain length (MCL) PHA, this fluorinated PHA was opaque, cream colored, and possessed greater crystallinity and a higher melting point (∼100 °C) than did the other MCL PHAs. Surface contact angle evaluation revealed that the PHA with two fluorine atoms possessed water-shedding properties. The number of substituted fluorine atoms in the carbon source affected cell growth and difluorine-substituted phenoxyalkanoic acids reduced cell growth, and polymer production compared to non-substituted phenoxyalkanoic acids. No polymeric materials were obtained using either 2,4,6TFPUDA or 2,3,4,5,6PFPUDA.     

Intramolecular photoreactions of 4-(ω-alkenyloxy)-6-methyl-2-pyrones

Photoirradiations of 4-(ω-alkenyloxy)-2-pyrones 1 gave site- and regio-specific intramolecular [2 + 2]-cycloadducts 2 being oxatricyclic lactones, and/or Dewar-type valence-isomer derivatives 4. The reaction path depended upon the alkenyl chain length. Namely the two or three carbon chain gave rise to intramolecular [2 + 2]-cycloaddition, while the four carbon chain caused both valence-isomerization and cycloaddition. Hydrolysis of the cycloadducts 2 gave oxabicycloalkanecarboxylic acids 7.     

A mild and facile synthesis of carboxylic anhydrides

Reaction of carboxylic acids with trimethylsilylethoxyacetylene in an inert solvent under mild conditions affords the corresponding carboxylic anhydrides in almost quantitative yields.     

Evaluation and comparison of high-sensitivity immunoradiometric assay kits for thyroid stimulating hormone

Fundamental and clinical characteristics of 3 kinds of high-sensitivity immunoradiometric assay (IRMA) kits for thyroid stimulating hormone (TSH). i.e., RIA BEADS II (kit A), TSH kit Daiichi II (kit B) and Ab tube TSH 'Eiken' (kit C) and one conventional radioimmunoassay (RIA) kit, i.e., TSH kit Daiichi (kit D), were studied. In the recovery test and the reproducibility test, there was no significant difference between the 4 kits. The sensitivities of kits A, B and C were much higher than that of kit D, and those IRMA kits were sensitive enough to distinguish hyperthyroidism from normal samples. For low concentrations of TSH (less than 5 microU/ml), the data from kits D, B, C and A tended to show higher values in that order. The correlation between the data measured by kits B and D, and the tendency of kit A toward lower values agreed well with other reports.