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31.
Racemic 2-amino-3-(heteroaryl)propanoic acids (1), mostly with a furan or thiophene nucleus as a heteroaryl group, were synthesized in 48-94% yield by the reduction of 3-(heteroaryl)-2-(hydroxyimino)propanoic acids (5) with zinc dust and formic acid in the presence of a catalytic amount of iron dust at 60 degrees C for 2 h. Under these conditions, unfavorable hydrogenolysis of bromine on the thiophene nucleus does not occur. Traditional N-formylation of the prepared 3-(heteroaryl)alanine (1) with a mixture of formic acid and acetic anhydride afforded 2-(formylamino)-3-(heteroaryl)propanoic acids (6) in 51-95% yield. 相似文献
32.
The aqueous solution of mixture of sodium decyl sulfate (SDeS) and decyltrimethylammonium bromide (DeTAB) has been found to form equilibrium multilamellar vesicles (MLV) spontaneously. We measured the surface tension of the aqueous solution of 1:1 mixture of SDeS and DeTAB as a function of temperature T at various molalities m under atmospheric pressure. The surface density, the entropy of adsorption and the entropy of vesicle formation are evaluated and compared with those of the decyltrimethylammonium decyl sulfate (DeTADeS) aqueous solution system to investigate the role of small counterions in the mechanism of equilibrium vesicle formation. The saturated surface density Gamma (H,C ) vs T curve of the SDeS/DeTAB system sits below that of the DeTADeS system. Therefore, sodium and bromide ions are negatively adsorbed and nevertheless, they neutralize the electric charge of the decyl sulfate ion DeS(-) and the decyltrimethylammonium ion DeTA(+) to some extent to weaken the electrostatic attraction between the polar head groups in the adsorbed film. The net surfactant concentration required for vesicle formation was larger in the SDeS/DeTAB system. Hence, the electrostatic attraction between the polar head groups of the surfactant ions which is one of the major driving forces for vesicle formation is weakened by the presence of the counterions Na(+) and Br(-). Small but distinct changes in the surface density and the entropies of MLV formation of the SDeS/DeTAB system from those of the DeTADeS system were also found. 相似文献
33.
The pinacol reaction of beta-halogenated alpha,beta-unsaturated aldehydes was promoted by titanium tetraiodide to give coupling products in good yields with high dl-selectivity. Subsequent reduction with H(2)/Pd-C gave saturated vic-diols in good yields. Heck coupling reaction enabled the displacement of halogens with vinyl groups without the loss of stereochemical integrities. [reaction: see text] 相似文献
34.
Seto Y. Umemoto K. Arii T. Masuda Y. 《Journal of Thermal Analysis and Calorimetry》2004,76(1):165-177
New solid complex of nitrilotriacetic acid and bismuth trichloride was synthesized by a solid phase reaction of nitrilotriacetic
acid and bismuth trichloride at room temperature. The composition of the sample is BiCl3[N(CH2COOH)3]2.5. The crystal structure of the complex belongs to triclinic system with the lattice parameters: α=0.7849 nm, β=0.9821 nm,
χ=2.0021 nm, α=96.50°, β=98.76° and γ=90.49°. The far-infrared spectra show the bonding between the Bi ion and N atom of nitrilotriacetic
acid. The thermal analysis also demonstrates the complex formation between the bismuth ion and nitrilotriacetic acid. The
gaseous pyrolysis product and the final residue in the thermal decomposition process are determined to check the thermal decomposition
reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
35.
Chiral β-dimethylaminoalkylphosphines were prepared starting with amino acids, (S)-alanine, (S)-phenylalanine, (R)-phenylglycine, (S)-valine, and (R)-tert-leucine. The chiral phosphines were found to be highly efficient ligands for a nickel catalyzed asymmetric Grignard cross-coupling reaction (38~94% optical yield). 相似文献
36.
[structure: see text] A highly convergent synthetic route to the FGHIJKLM ring fragment of ciguatoxins has been developed, which relied on extensive use of the B-alkyl Suzuki-Miyaura coupling reaction. 相似文献
37.
The relative stability of various organosulfur radicals is estimated by competitive elimination technique using tributyltin radical and acetophenone derivatives having two different sulfur substituents at α and α positions. 相似文献
38.
Mitsuo Ishikawa Takamasa Fuchikami Makoto Kumada 《Journal of organometallic chemistry》1978,162(2):223-238
Photolysis of phenylpentamethyldisilane, 1,1-diphenyltetramethyldisilane and 1-isopropyl-1-phenyltetramethyldisilane in the presence of a wide variety of olefins has been studied. All reactions investigated, with the exception of those with 1-methylcyclohexene and tetramethylethylene, afforded the corresponding 1/1 addition products. Yields of the adducts depended highly on the structure of the olefins used. In the photolysis of phenylpentamethyldisilane in the presence of an equimolar mixture of 1,1- and 1,2-bis(trimethylsilyl)ethene under competitive reaction conditions, the main product was the one arising from the 1,1-isomer. A possible mechanism for the process of addition of olefin to the photochemically generated silicon-carbon double-bonded intermediate (A) is discussed. 相似文献
39.
Makoto?OhtsukaEmail author Christina?Wedel Kimio?Itagaki 《Monatshefte für Chemie / Chemical Monthly》2005,136(11):1909-1914
Summary. Isothermal sections of the Ni–Mn–Ga ternary phase diagram at 1073 and 1273 K were investigated over a wide range of alloy
compositions. The range of the β-Ni2MnGa phase, its equilibria with the γ-(Mn, Ni), α′-Ni3Ga, and γ-Ni3Ga2 phases, and the liquidus and solidus lines were determined experimentally. The aging effect on the shape memory effect (SME)
of Ni2MnGa sputtered films was also investigated. The two-way SME of the constraint-aged films was confirmed by the temperature
change. 相似文献
40.
[structure: see text] The first total synthesis of gambierol, a marine polycyclic ether toxin, has been achieved. The synthesis features the Pd(PPh3)4/CuCl/LiCl-promoted Stille coupling for the stereoselective construction of the sensitive triene side chain that includes a conjugated (Z,Z)-diene moiety. 相似文献