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.     

Structural and conformational studies on euphornin and related diterpenes

In addition to euphornin, three new toxic substances (euphornins A, B and C) have been isolated from the plant $\text{Euphorbia}$$\text{helioscopia}$ L., and their absolute stereostructures also been elucidated on the basis of their spectral data and some chemical evidence together with an X-ray crystallographic analysis of the p-bromobenzoate derived from euphornin. Furthermore, their conformations have also been discussed.     

Two-dimensional folded chain crystals of a synthetic polymer in a Langmuir-Blodgett film

Isotactic poly(methyl methacrylate) monolayers deposited from a water surface onto mica at different surface pressures were studied by atomic force microscopy, and their structure formation from single chains to two-dimensional folded chain crystals was clearly observed. Furthermore, gentle crystallization of the monolayer by slow compression on the water surface enabled the observation of crystals at a molecular level, thus visualizing the chain foldings and tie-chains for the first time. The resulting molecular level information will provide an important clue toward the understanding of polymer crystals not only in two dimensions but also in three dimensions.     

Synthesis, isolation via self-assembly, and single-molecule observation of a [60]fullerene-end-capped isotactic poly(methyl methacrylate)

We report the preparation and single-molecule observation of a high molecular weight C60-end-capped, stereoregular poly(methyl methacrylate) (PMMA-C60) with a precisely controlled structure. The highly isotactic PMMA-C60 (mm = 98%) with a narrow molecular weight distribution was synthesized by the stereospecific anionic living polymerization of tert-butyl methacrylate followed by end-capping with C60, hydrolysis of the pendant esters, and methylation with CH3I. Although the functionality of the C60 (fC60) of the as-prepared isotactic PMMA was imperfect (ca. 40%), the completely C60-end-capped PMMA (fC60 approximately 100%) was successfully isolated through self-assembly of the PMMA-C60 in a polar solvent by size exclusion chromatography. Furthermore, the individual PMMA chains together with the covalently bonded terminal C60 molecules were clearly visualized by atomic force microscopy, which definitely showed the structure of the isolated PMMA-C60.     

Plasma polymerization of mixed monomer gases

In this paper, plasma polymerization of mixed monomer gases was studied. In the films, the elements derived from each monomer are contained, and they are distributed homogeneously at a certain depth. The films are made up by the copolymers in which both monomers are combined. The chemical compositions of the copolymers can be controlled by changing the proportions of the two monomer gases. The films having gradual compositional change toward depth can be prepared by using a mixture of two monomer gases and changing their proportions during the plasma polymerization. These copolymeric and gradient copolymeric films were formed on porous glass hollow fibers, and gas permeability of these composite membranes was measured. The gradient copolymerization methods are available for the preparation of the membranes for gas separation.     

Effect of solvent on radical polymerization of vinyl benzoate

Absolute rate constants of the vinyl benzoate polymerization have been measured by use of the intermittent illumination method in various aromatic solvents and ethyl acetate at 30°C. The determination of absolute rate constants showed that effects of solvent on the polymerization rate of vinyl benzoate were mainly ascribed to the variation of k_p values with solvents rather than that of k_t values. The k_p values for solvents used increased in the order: benzonitrile < ethyl benzoate < anisole < chlorobenzene < benzene < fluorobenzene < ethyl acetate. There was an eightfold difference between the largest and the smallest values The large variation among k_p values was explained neither by the copolymerization through solvents nor the chain transfer to solvents, but by a reversible complex formation between the propagating radical and aromatic solvents. This explanation was supported by a correlation between k_p values and calculated delocalization stabilizations for the complexes.     

Facile oxidative conversion of hydrazides of carboxylic acids to corresponding acids,esters and amides using copper compounds

Oxidative conversion of hydrazides of carboxylic acids to acids, esters and amides using Cu salts was studied. Acids were obtained in high yields by using a catalytic amount of Cu(OAc)₂ at room temperature by bubbling oxygen. Hydrazides were converted to esters by the treatment with Cu(OR)Cl or Cu(OR)₂ formed in situ from CuCl₂ and sodium alkoxide. Amides were obtained in high yields by the oxidation of hydrazides with CuCl₂ in the presence of amines.     

Preparation of five- and six- membered cyclic ketones by the palladium-catalyzed cyclization reaction. Application to methyl dihydrojasmonate synthesis

Methyl 3-oxo-8-phenoxy-6-octenoate ($\text{1}$) was cyclized using Pd(OAc)₂-PPh₃ as a catalyst to give 2-carbomethoxy-3-vinylcyclopentanone ($\text{2}$) and 2-carbomethoxy-4-cycloheptenone ($\text{3}$). The former was the main product in acetonitrile. 2-Alkylated 3-oxo-8-phenoxy-6-octenoates were converted mainly to the five-membered ketones. Based on this cyclization method, methyl dihydrojasmonate ($\text{8}$) was prepared from methyl 2-pentyl-3-oxo-8-phenoxy-6-octenoate ($\text{5}$). Methyl 3-oxo-9-phenoxy-7-nonenoate (10) was subjected to the palladium-catalyzed cyclization to afford 2-carbomethoxy-3-vinylcyclohexanone (11) selectively without forming the eight-membered ketone (12).     

The electronic spectrum and electronic structure of 1,5 dinitronaphthialene

The electronic absorption spectra of the n-heptane and ethanol solutions and the polarized absorption spectrum of the single crystal were measured with 1,5-dinitronaphthalene. 1,5-Dinitronaphthalene shows three absorption bands at 198.7, 230 and 323 m. The 230 m and 323 m. bands are polarized almost parallel with the long and short axes of the naphthalene ring respectively. The assignment of the bands has been made by combining the observed results with the theoretical consideration.

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Zusammenfassung Das UV-Absorptionsspektrum von 1,5-Dinitronaphthalin in Lösung von n-Heptan und Äthanol und das Polarisationsabsorptionsspektrum des Einkristalls wurde aufgenommen. Es zeigt drei Banden bei 198,7, 230 und 323 m, wobei die Polarisationsrichtungen der beiden letzteren nahezu parallel zur langen und kurzen Achse des Naphthalinringes liegen. Die Zuordnung der Banden wurde auf Grund einer Kombination experimenteller und theoretischer Gegebenheiten vorgenommen.

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Résumé Le spectre électronique d'absorption du 1,5-dinitronaphthalène a été mesuré dans l'éthanol, le n-heptane et dans le monocristal. Des bandes à 198,7, 230 et 323 m la deuxième (troisième) est polarisée presque parallèle à l'axe longue (courte) du noyau naphthalénique. La comparison aux résultats théoriques permet l'interprétation des bandes.

     

Topical application of a novel, water-soluble gamma-tocopherol derivative prevents UV-induced skin damage in mice

We investigated whether the topical application of a novel, water-soluble gamma-tocopherol (gamma-Toc) derivative, gamma-tocopherol-N,N-dimethylglycinate hydrochloride (gamma-TDMG), could protect against UV-induced skin damage in hairless mice. Topical pre- or post-application of a 5% (93 mM) gamma-TDMG solution in water/propylene glycol/ethanol (2:1:2) significantly prevented sunburn cell formation, lipid peroxidation and edema/inflammation that were induced by exposure to a single dose of UV irradiation of 5 kJ/m2 (290-380 nm, maximum 312 nm). This effect was greater than that seen with two alpha-Toc derivatives, alpha-tocopherol acetate (alpha-TA) and alpha-tocopherol-N,N-dimethylglycinate (alpha-TDMG). When a 5% solution of gamma-TDMG was applied to mouse skin for 1 h, cutaneous gamma-Toc increased by 25-fold after 24 h; levels of cutaneous alpha-Toc increased by only two- and eight-fold in alpha-TDMG and alpha-TA treated skins, respectively. These findings indicated that gamma-TDMG immediately converted to gamma-Toc in the skin and suggest that ability of gamma-TDMG to protect the skin from the damaging effects of irradiation was due to its conversion to gamma-Toc. When a 5% solution of gamma-Toc was applied to mouse skin for 1 h, cutaneous gamma-Toc rapidly increased by 25-fold, but fell to baseline levels by 24 h. In contrast, the concentration of gamma-Toc in skin that was treated with gamma-TDMG similarly increased, but these high levels were maintained after 24 h. These results suggest that gamma-TDMG may be a more effective source of gamma-Toc in skin. Thus, the topical application of gamma-TDMG may be efficacious for the prevention of UV-B-induced skin damage.