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31.
1,1-Diaryl-1-penten-4-yn-3-ols react with diphenylphosphine oxide in the presence of a thiolate-bridged diruthenium complex as a catalyst and give high yields of aryl(diphenyl)phosphine oxide products via an initial substitution followed by a cyclization at the produced allene intermediate. [reaction: see text] 相似文献
32.
The highly specific molecular recognition of a twisted hexaporphyrin complex, tris[5,5'-bis[5,10,15-tris[methoxy(ethoxy)(2)carbonylethyl]porphyrinatozinc(II)]-2,2'-bipyridine]ruthenium(II) chloride (2), is described. Complex 2 has two trisporphyrin binding sites and can bind two triamines, tris(2-aminoethyl)amine (3) (K(1) = 3.0 x 10(8) M(-1), K(2) = 3.0 x 10(7) M(-1)), 1,1,1-tris(aminomethyl)ethane (4) (K(1) = 2.0 x 10(7) M(-1), K(2) = 1.4 x 10(6) M(-1)), tris(3-aminopropyl)amine (5) (K(1) = 3.5 x 10(6) M(-1), K(2) = 6.0 x 10(6) M(-1)), and 1,3,5-tris(aminomethyl)benzene (6) (K(1) = 2.9 x 10(6) M(-1), K(2) = 1.2 x 10(6) M(-1)), strongly with its torsional motion. The 1:2 complex between 2 and the best fit triamine 3 showed the nature of the specific rigid structure in the UV-vis, fluorescence, and (1)H NMR spectra and isothermal titration calorimetry (ITC) measurements. 相似文献
33.
[reaction: see text] Double phosphinylation of propargylic alcohols with diphenylphosphine oxide in the presence of a thiolate-bridged diruthenium complex as catalyst gives the corresponding 2,3-bis(diphenylphosphinyl)-1-propenes in high yields with a complete selectivity. 相似文献
34.
Toshiyuki Uryu Toshiyuki Seki Tokiji Kawamura Akashi Funamoto Kei Matsuzaki 《Journal of polymer science. Part A, Polymer chemistry》1976,14(12):3035-3044
The stereoregularity of polystyrene prepared by anionic polymerization was determined by means of 13C-NMR spectroscopy. The stereoregularity changed with such polymerization conditions as catalyst, solvent, and temperature. Sodium naphthalene as catalyst gave a syndiotactic-rich polystyrene of 66–68% syndiotactic dyads independently of solvent and temperature, while potassium and cesium naphthalenes as catalyst produced polystyrenes with different stereoregularities ranging from syndiotactic-rich to isotactic-rich configurations, depending on solvent and temperature. The mechanism of anionic polymerization which caused the difference in stereoregularity was discussed from the viewpoint of growing ionic species. 相似文献
35.
Masahiro Manabe Asako Tokunaga Hideo Kawamura Hajime Katsuura Masaki Shiomi Koichi Hiramatsu 《Colloid and polymer science》2002,280(10):929-935
In the micellar solution of SDS, the partition coefficient (Kx) of following branched alkanols at infinite dilution was determined by applying a differential conductivity method: the alkanols used were i-CmH2m+1OH (m=4-9, i=1-5) in which the position of OH group (i) shifts from an end to the center of a hydrocarbon chain. The method provides two significant quantities, d!/dXam and dCsf/dCaf in addition to Kx. The following results have been obtained. (1) The dependence of Kx on i indicates that the hydrophobicity of alkanol is weakened with increasing i, whereas the increase in m strengthens the hydrophobicity. (2) The degree of counterion disossiation of micelles (!) is accelerated by the solubilized alkanols in micelles (mole fraction: Xam) and the acceleration rate, d!/dXam (=0.17), depends on neither m nor i. (3) In the bulk water, the monomerically dissolved alkanols (concentration: Caf) depresses the concentration of free monomer surfactant (Csf), and the depressing rate, dCsf/dCaf, in micellar solution is identical with the corresponding quantity, ((CMC/(Ca)o at CMC. 相似文献
36.
Fujii H Hirano N Uchiro H Kawamura K Nagase H 《Chemical & pharmaceutical bulletin》2004,52(6):747-750
7beta-Carbamoyl-4,5alpha-epoxymorphinans 5 were stereoselectively synthesized from the 7alpha-carboxylate intermediate 3 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and amines under reflux conditions in mesitylene via a novel and reactive gamma-lactone 7. These were the first examples of the stereoselective syntheses of 7beta-substituted 4,5alpha-epoxymorphinans. The mechanism of the reaction process was elucidated as follows: 1) epimerization of 7alpha-carboxylate 3, 2) intramolecular lactonization of 7beta-carboxylate 6, and 3) aminolysis of the resultant gamma-lactone 7. The aminolysis of the isolated reactive gamma-lactone 7 with allylamine and the alcoholysis with MeOH in the presence of NaBH(4) proceeded at room temperature. The gamma-lactone 7 can be a useful intermediate for the preparation of 7beta-substituted 4,5alpha-epoxymorphinans that would be potent selective delta opioid receptor ligands. The stereoselective syntheses of the 7alpha-carbamoyl-4,5alpha-epoxymorphinans 9 from 7alpha-carboxylate 3 via 7alpha-carboxylic acid were also successful. 相似文献
37.
Yagi Kiyohito Hamada Kenji Hlrata Kazumasa Miyamoto Kazuihisa Miura Yoshiharu Akano Tohru Fukatu Kiyomi Ikuta Yoshiaki Nakamura Hiroshi K. 《Applied biochemistry and biotechnology》1994,(1):225-232
A marine green alga,Chlamydomonas sp. strain MGA161 was cultivated under illumination of red and white lights. The growth rate under red light illumination
was almost the same as that in the basic conditions under white light illumination, but red light-grown cells accumulated
almost twice as much starch as white light-grown cells. Although there was a slight decrease in carbonic anhydrase activity,
red light-illuminated cells had almost 2.3 times the fructose-l,6-diphos-phatase activity of white light-illuminated cells.
Red light might stimulate starch accumulation by increasing the amounts of enzymes related to carbon fixation through the
phytochrome system. Cells grown under red light degraded 1.6 times as much starch and produced 1.7 times as much hydrogen
and 1.6 times as much ethanol compared with cells grown under white light during 12 h of dark anaerobic fermentation. 相似文献
38.
Nakao Y Imanaka H Sahoo AK Yada A Hiyama T 《Journal of the American Chemical Society》2005,127(19):6952-6953
Alkenyl- and aryl[2-(hydroxymethyl)phenyl]dimethylsilanes, highly stable tetraorganosilicon reagents, are found to react with aryl and alkenyl iodides in the presence of a palladium catalyst and K2CO3 as a base, significantly milder conditions compared with those ever reported for the silicon-based cross-coupling reactions. The reaction tolerates a wide range of functional groups, including silyl protectors, and allows a gram-scale synthesis to recover and reuse the silicon residue. 相似文献
39.
Yoshiaki Hidaka Hiromitsu Masaoka Hidekazu Oshita Takuji Nakamura Koji Tanaka Hiroyuki Kawano 《国际化学动力学杂志》1992,24(10):871-885
The thermal decomposition of vinylacetylene (C4H4) was studied behind reflected shock waves using both a single-pulse method (reaction time between 0.8 and 3.3 ms) and a time-resolved UV-absorption method (230 nm). The studies were done over the temperature range of 1170–1690 K at the total pressure range of 1.3–2.3 atm. The mechanism was used to interpret both the early and late stages of vinylacetylene decomposition at the high temperatures. It was confirmed that C4H4 dissociation proceeded through the following three channels. The rate constant expression of reaction (1) was determined as k1 = 6.3 × 1013 exp(?87.1 kcal/RT) s?1. The rate constants of the succeeding reactions (chain reaction, C4H4 + H → i-C4H3 + H2 and C4H4 + H → C2H2 + C2H3 and decomposition reactions of free radicals, i-C4H3 + M → C4H2 + H + M) were confirmed or estimated. © John Wiley & Sons, Inc. 相似文献
40.
Sulfuric acid catalyzed ring contractions with extrusion of a methyl group were examined for alcohol and olefin derivatives (28–31) of endo-2,8-trimethylene-cis-bicyclo[3.3.0]octane (11), which was one of the two possible progenitors, among altogether 69 isomers, for methylperhydrotriquinacenes (6, 7 and 12), the only methyltricyclodecane intermediates found so far, in the tricycloundecane rearrangement. Only minor amounts (1.6–2.0%) of methylperhydrotriquinacenes were formed from these reactants 28–31, and the results support the earlier theoretical conclusion that the methyl extrusions were in general energetically quite unfavorable processes owing to the formation of primary carbinyl cations at the expense of more stable secondary bridge or tertiary bridgehead ones. Reaction pathways for these precursors 28–31 were discussed with reference to those of perhydrotriquinacene 2-carbinyl cations (33a's), which corresponded to some of the ring contraction product cations from 28–31. 相似文献