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781.
Toshio Tanaka Seizi Kurozumi Takeshi Toru Makiko Kobayashi Shuji Miura Sachio Ishimoto 《Tetrahedron》1977,33(10):1105-1112
Regiospecific α-acylation of β-alkenylated enolates generated by conjugate addition of lithium organocuprates to α,β-unsaturated ketones is described. Several new 7-oxoprostaglandin analogues, 7-oxoprostaglandin E1 (18), 11-deoxy-7-oxoprostaglandin E1 (23), and their 15-epi enantiomers 17 and 22, were synthesized by conjugate addition-acylation method. From optically active 4(R) -t - butyldimethylsiloxycyclopent - 2 - en - 1 - one (R-11), 7-oxoprostaglandin E1 (18) was synthesized. Determination of the absolute configuration of 11-deoxy-7-oxoprostaglandin E1 (23) and its 15-epi enantiomer (22) on the basis of CD study is described. Successful acylation of β-alkenylated lithium copper enolates with reactive acylating agents such as thiol esters and N-acyl imidazole as well as acyl halides is described. 相似文献
782.
783.
Kadish KM Autret M Ou Z Akiba Ky Masumoto S Wada R Yamamoto Y 《Inorganic chemistry》1996,35(19):5564-5569
The following five antimony(V) tetraphenylporphyrins with sigma-bonded antimony-carbon bonds were synthesized: [(TPP)Sb(CH(3))(2)](+)PF(6)(-), [(TPP)Sb(OCH(3))(OH)](+)PF(6)(-), [(TPP)Sb(CH(3))(OH)](+)ClO(4)(-), [(TPP)Sb(CH(3))(OCH(3))](+)ClO(4)(-), and [(TPP)Sb(CH(3))(F)](+)PF(6)(-). Each compound is stable toward air and moisture and has a high melting point (>250 degrees C). The electrochemistry and spectroelectrochemistry of these sigma-bonded porphyrins were examined in benzonitrile or dichloromethane containing 0.1 M tetrabutylammonium perchlorate as supporting electrolyte and the data compared to those for three previously synthesized OEP derivatives containing similar sigma-bonded and/or anionic axial ligands. Each porphyrin shows two reversible reductions and up to a maximun of one oxidation within the potential window of the solvent. Spectroelectrochemical data indicate formation of a porphyrin pi anion radical upon the first reduction as do ESR spectra of the singly reduced species. However, a small amount of the Sb(III) porphyrin products may be generated via a chemical reaction following electron tranfer. An X-ray crystallographic analysis of [(TPP)Sb(CH(3))(F)](+)PF(6)(-) is also presented: monoclinic, space group C2/c, Z = 8, a = 24.068(5) ?, b = 19.456(4) ?, c = 18.745(3) ?, beta = 94.69(2) degrees, R = 0.056. 相似文献
784.
Sumanta Bhattacharya Takanori Shimawaki Xiaobin Peng A. Ashokkumar Shuji Aonuma Takahide Kimura Naoki Komatsu 《Chemical physics letters》2006,430(4-6):435-442
We have tailored some interesting mono- and diporphyrins, viz., 5, 10, 15, 20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (TP), 5, 15-bis(3, 5-dioctylphenyl)-2, 8, 12, 18-tetramethyl-3, 7, 13, 17-tetradodecyl-21H,23H-porphyrin (AP) and 1, 3-bis(10′,20′-diundecyl-21′H,23′H-porphyrin-5′-yl)benzene (DP) as host molecules to study their complexation behavior with C60 and C70. Fluorescence spectroscopic measurements showed that emission of TP, AP and DP in toluene was quenched in the presence of C60 or C70. Large binding constants (K) in the magnitude of 1.5 × 104 dm3 mol−1 have been obtained for the 1:1 complexes of C70 with TP, AP and DP. However, the C60 complexes have exhibited 8.5 times smaller K compared to C70 complexes. Ab initio theoretical calculations give a good support in favor of strong complexation between C70 and porphyrins. 相似文献
785.
M Miwa T Ishikawa H Eda M Ryu K Fujimoto Y Ninomiya I Umeda K Yokose H Ishitsuka 《Chemical & pharmaceutical bulletin》1990,38(4):998-1003
N4-Trimethoxybenzoyl-5'-deoxy-5-fluorocytidine (Ro 09-1390), a new prodrug of 5'-deoxy-5-fluorouridine (5'-dFUrd), was synthesized for the purpose of finding a drug with less intestinal toxicity than the parent compound. The present study compared the antitumor activity and immunotoxicity of Ro 09-1390 with those of 5'-dFUrd, 5-fluorouracil (5-FUra) and tegafur in various transplantable tumor models. The antitumor efficacy of Ro 09-1390 was comparable to 5'-dFUrd and these two agents were much more effective than the others. However, Ro 09-1390 was much less toxic to the intestinal tract and less immunosuppressive in both humoral and cellular immune reactions than 5'-dFUrd. Consequently, Ro 09-1390 showed higher therapeutic indices and higher efficacy than 5'-dFUrd at high dosages. The antitumor spectrum of Ro 09-1390 was somewhat different from that of 5'-dFUrd, though it shows the efficacy after it converts to 5'-dFUrd. The activity of Ro 09-1390 was partly associated with cytidine deaminase in the tumors treated. Ro 09-1390 appeared to be more effective against tumors with a high concentration of the enzyme by which the major metabolite 5'-deoxy-5-fluorocytidine (5'-dFCyd) is metabolized to 5'-dFUrd. 相似文献
786.
Iwaoka M Komatsu H Katsuda T Tomoda S 《Journal of the American Chemical Society》2002,124(9):1902-1909
To evaluate weak intramolecular nonbonded Se...F interactions recently characterized for a series of o-selenobenzyl fluoride derivatives (Iwaoka et al., Chem. Lett. 1998, 969-970), the temperature dependence of the nuclear spin coupling between Se and F (J(Se...F)) was investigated for 2-(fluoromethyl)phenylselenenyl cyanate (1a) and bis[2-(fluoromethyl)phenyl] diselenide (1e) in CD2Cl2 and CD3CN. A significant increase in the magnitude of J(Se...F) was observed for both 1a and 1e upon lowering temperature, whereas the values of J(Se...F) for the corresponding trifluoromethyl compounds slightly reduced or remained unchanged at low temperatures. Application of the rapid equilibrium model between two possible conformers revealed that conformer A with an intramolecular Se...F interaction is more stable in enthalpy (DeltaH) by 1.23 kcal/mol for 1a (in CD2Cl2) and by 0.85 and 0.83 kcal/mol for 1e (in CD2Cl2 and CD3CN, respectively) than conformer B, which does not have close Se...F contact. The negligible solvent effects for 1e suggested marginal electrostatic nature of the Se...F interactions. Instead, importance of the n(F) -->sigma*(Se-X) orbital interaction was suggested by quantum chemical (QC) calculations and the natural bond orbital (NBO) analysis. 相似文献
787.
In situ chemical aminoacylation with amino acid thioesters linked to a peptide nucleic acid 总被引:1,自引:0,他引:1
Ninomiya K Minohata T Nishimura M Sisido M 《Journal of the American Chemical Society》2004,126(49):15984-15989
tRNA-specific chemical aminoacylation was achieved with nonnatural amino acids. A nonnatural amino acid was activated as a thioester derivative, and the latter was linked through a spacer to the N-terminal of a 9-mer peptide nucleic acid that is complementary to the 3'-terminal region of yeast phenylalanine tRNA. Efficient aminoacylation was observed when the amino acid thioester-spacer-PNA conjugate was mixed with the tRNA. The PNA-assisted aminoacylation was also successful in an Escherichia coli in vitro protein synthesizing system that contained an orthogonalized tRNA. The in situ aminoacylation/in vitro translation gave a mutant protein in which the nonnatural amino acid was incorporated into the position directed by a CGGG 4-base codon/anticodon pair. 相似文献
788.
Okawara T Ehara S Kagotani H Okamoto Y Eto M Harano K Yamasaki T Furukawa M 《The Journal of organic chemistry》1996,61(12):4125-4129
Hydrazinoethanols 1 were reacted with aldehydes 2 and 6 and glutaraldehyde (14) in aqueous solution to give dioxatetraazaperhydroanthracenes 3, 7, 12, and 13 and -perylenes 15 in yields of 19-88 and 42-72%, respectively. Compounds 3, 7, 12, and 15 were deduced by (13)C-NMR spectra to have two C(2) symmetry axes, while compound 12 was shown to have a symmetry axis by X-ray crystallography. The most favorable stereoisomers were consistent with predictions obtained by the semiempirical molecular orbital method AM1. The structure of compound 15 was confirmed by X-ray crystallography. 相似文献
789.
790.
Chika Takai Tadashi Hotta Shuji Shiozaki Shuhei Matsumoto Takehisa Fukui 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,373(1-3):152-157
A solid-in-oil-in-water (S/O/W) emulsion system has been developed to prepare porous polymeric microspheres. The obtained microspheres showed unique core–shell structure with a dense core and a surface porous layer. The emulsion system has two processes. In the first process, S/O/W1 viscous emulsion is prepared by dropping of S/O phase in the first water phase (W1). In the second process, the S/O/W1 emulsion is poured to another water phase (W2) as S/O/W1/W2 emulsion. During the process, S/O/W1 droplet becomes microsphere after organic medium completely diffusion. Emulsion techniques have various effective combinations such as additive and process conditions to design microsphere morphology. With regards to the proposed S/O/W system, addition of the solid phase in the system is a key factor to form the porous structure. When the medium diffusion starts, the solid makes W1 phase kept inside the S/O/W1 droplet. The remained W1 phase changes surface porous layer after purification. Affinity between the solid and oil phase should be adjusted as well. In this study, an optimization of the emulsion system was attempted considering solubility parameter and polarity. Additionally, it is found that process conditions could help to design microsphere morphology such as pore size and porous layer thickness. 相似文献