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941.
Kazuki Sato Takashi Suzuki Shinya Aoyama Naoyoshi Maki Yasuo Suzuki Masayuki Sato 《Tetrahedron》2007,63(32):7571-7581
To explore new inhibitors of the sialidase of human parainfluenza virus type 1 (hPIV-1), a series of novel Neu5Ac2en derivatives were synthesized. Thus, 8,9-O-isopropylidene-4-O-2-propynyl-Neu5Ac2en methyl ester 8 was subjected to a Sonogashira coupling reaction with a variety of heteroaryl halides to produce a series of 4-O-(3-heteroaryl-2-propynyl) compound 9. Treatment of 9 with 80% acetic acid followed by alkaline hydrolysis afforded deprotected Neu5Ac2en compounds. The 4-epi-analogs of this type of Neu5Ac2en were synthesized in a similar manner. Compound 5d showed the most potent inhibitory activity (IC50 1.2 μM) against hPIV-1 sialidase. 相似文献
942.
Masayuki Utsugi 《Tetrahedron letters》2007,48(39):6868-6872
Construction of the taxane skeleton via the stereoselective conjugate addition of cyanide and the intramolecular B-alkyl Suzuki-Miyaura coupling reaction is described. A conjugate addition of cyanide to enone 17 proceeded diastereoselectively to provide the desired 18 incorporating the correct C3 stereogenic center in the taxol C-ring. The intramolecular B-alkyl Suzuki-Miyaura coupling reaction of 22, which was derived from 18, successfully furnished the taxol B-ring in 81% yield. 相似文献
943.
944.
Mitsuhashi S Fukushima T Arai K Tomiya M Santa T Imai K Toyo'oka T 《Analytica chimica acta》2007,587(1):60-66
Kynurenine (KYN), a tryptophan metabolite, is a precursor of kynurenic acid, which is an antagonist of N-methyl-d-aspartate receptor. In this study, an enantiomeric separation of d,l-KYN derivatized with the benzofurazan fluorescence reagent 4-N,N-dimethylaminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) (DBD-d,l-KYN) was first investigated by using a high-performance liquid chromatography (HPLC) with several chiral columns. As a consequence, DBD-d,l-KYN was enantiomerically separated on a cellulose-type chiral column (CHIRALCEL OJ-RH) with a mobile phase of H2O/CH3CN/MeOH (40/50/10) containing 0.1% acetic acid. Under this condition, the separation factor and resolution were 1.48 and 1.28, respectively. Next, a column-switching HPLC consisting of both octadecylsilica and chiral columns was developed and used to determine both d- and l-KYN enantiomers in 10 μL of rat plasma following the intraperitoneal administration of d,l-KYN to rats (10 mg kg−1). The result revealed that the concentration of l-KYN was higher than that of d-KYN, suggesting that d-KYN was eliminated faster than l-KYN. 相似文献
945.
946.
Ando K Akai Y Kunitomo J Yokomizo T Nakajima H Takeuchi T Yamashita M Ohta S Ohishi T Ohishi Y 《Organic & biomolecular chemistry》2007,5(4):655-663
A novel seven-membered lactam formation method has been established by intramolecular ring closure reaction of 4-bromo-(E)-3-[(2-alkylvinyl)carbonylamino]benzo[b]furans under Heck coupling conditions. A number of furo[2,3,4-jk][2]benzazepin-4(3H)-ones, tricyclicbenzo[b]furans, have been prepared by this method and evaluated for their leukotriene B(4) (LTB(4)) receptor and poly(ADP-ribose)polymerase-1 (PARP-1) inhibitory activities. 相似文献
947.
Hf(1-x)Lu(x)W(2)O(8-y) solid solutions up to x = 0.04, based on a negative thermal expansion material HfW(2)O(8), were synthesized by a solid state reaction method. X-ray diffraction experiments of these solid solutions from 90 to 560 K indicated thermal contraction with increasing temperature. Temperatures of order-disorder phase transition (T(trs)) associated with the orientation of WO(4) tetrahedra were determined from disappearance of a characteristic diffraction peak (310). The T(trs) of the solid solutions drastically decreased with increasing Lu content. Saturated order parameters (eta(s)) associated with the orientational order of the WO(4) pairs were estimated from the characteristic diffraction peak at sufficient low temperature. These behaviors of Hf(1-x)Lu(x)W(2)O(8-y) are consistent with those of Zr(1-x)M(x)W(2)O(8-y) (M = Sc, Y, In, Lu). The drastic suppression of T(trs) in Hf(1-x)Lu(x)W(2)O(8-y) can be interpreted in the framework of a model proposed for Zr(1-x)M(x)W(2)O(8-y), which states the existence of a local nanoregion including the WO(4) pairs having the frozen-in orientational disorder. To understand the substitution effect on the order-disorder phase transition comprehensively, classification based on the saturated order parameter eta(s) of the phase transition of AW(2)O(8) (A = Hf, Zr)-based solid solutions was carried out and discussed. 相似文献
948.
Tsuji M Hashimoto M Nishizawa Y Kubokawa M Tsuji T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(2):440-452
Microwave (MW) rapid heating has received considerable attention as a new promising method for the one-pot synthesis of metallic nanostructures in solutions. In this concept, advantageous application of this method has been demonstrated by using some typical examples for the preparation of Ag, Au, Pt, and AuPd nanostructures. Not only spherical nanoparticles, but also single crystalline polygonal plates, sheets, rods, wires, tubes, and dendrites were prepared within a few minutes under MW heating. Morphologies and sizes of nanostructures could be controlled by changing various experimental parameters, such as the concentration of metallic salt and surfactant polymer, the chain length of the surfactant polymer, the solvent, and the reaction temperature. In general, nanostructures with smaller sizes, narrower size distributions, and a higher degree of crystallization were obtained under MW heating than those in conventional oil-bath heating. The origin of these characteristic features under MW irradiation is discussed in terms of thermal and non-thermal effects under MW irradiation. 相似文献
949.
Rodolfo?R.?LlinásEmail author Kerry?D.?Walton Masayuki?Nakao Ian?Hunter Patrick?A.?Anquetil 《Journal of nanoparticle research》2005,7(2-3):111-127
Electrical recording from spinal cord vascular capillary bed has been achieved demonstrating that the intravascular space may be utilized as a means to address brain activity with out violating the brain parenchyma. While the initial demonstration was implemented using electrically insulated platinum electrodes in vitro, the possibility of using conducting polymer filaments is now being explored. This paper presents a set of highly possible future scenarios where the integration of electrophysiology and novel polymer technology may serve as a new approach towards basic and medical neuroscience.This revised version was published online in August 2005 with a corrected issue number. 相似文献
950.
We developed a confocal Raman microspectroscopy system combined with a laser trapping technique and applied it to aqueous solutions (H(2)O and D(2)O) of poly(N-isopropylacrylamide) (PNIPA), which is well-known as a representative thermo-responsive polymer, i.e., phase transition/separation between coiled and globular states. By introducing a near-infrared (1064 nm) laser beam into a microscope, PNIPA microparticles were produced at the focused spot of the laser beam, both in H(2)O and D(2)O. By using the present system, we succeeded in obtaining the Raman spectra of PNIPA in the coiled and globular states over a wide wavenumber region (800-3500 cm(-1)) for the first time. For the D(2)O solutions (in which the photothermal effect is negligible and hence the microparticles should be produced purely by the effect of radiation pressure), some significant differences were observed in the Raman spectra for the coiled state, in the globular state, and for laser induced microparticles. By analyzing these spectra in detail, we revealed that the structure of the laser-induced microparticles was analogous to that in the globular state. We also discuss the fundamental mechanism underlying the transformation of the higher order structure of a polymer by radiation pressure. 相似文献