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41.
Fluoro-homoneplanocin A (4) was synthesized from d-ribose, via the enyne ring-closing metathesis of 9, the stereoselective opening of epoxide 23a with fluoride, and a simultaneous oxidation-elimination reaction. The key intermediate 8 is expected to serve as a versatile intermediate for the synthesis of carbanucleosides. 相似文献
42.
Won Jun Choi Yun Jung Ko Girish Chandra Hyuk Woo Lee Hea Ok Kim Hyo Jung Koh Hyung Ryong Moon Young Hoon Jung Lak Shin Jeong 《Tetrahedron》2012,68(4):1253-1261
Conformationally restricted 2′-C-azido-, hydroxy- and fluoromethyl-carbanucleosides 4b–f were efficiently synthesized via the stereoselective conversion of ketone 7 to epoxide 14, followed by the stereoselective opening of the epoxide with nucleophiles (OAc, N3, and F), while the corresponding 2′-C-methyl-carbanucleoside 4a was synthesized via the stereoselective Grignard reaction of ketone 7 with methylmagnesium iodide as a key step. All the final nucleosides 4a–f were assayed for anti-HCV activity, but showed neither significant anti-HCV activity nor cytotoxicity in a cell-based replicon assay. 相似文献
43.
Stereoselective synthesis of novel 1'-alpha-substituted-4'-thionucleosides was achieved starting from D-gulonic acid gamma-lactone via stereoselective nucleophilic substitution. 相似文献
44.
Mazloumi M Zanganeh S Kajbafvala A Ghariniyat P Taghavi S Lak A Mohajerani M Sadrnezhaad SK 《Ultrasonics sonochemistry》2009,16(1):11-14
Cauliflower-like ZnO nanostructures with average crystallite size of about 55 nm which have surface one dimensional (1D) nanoarrays with 10 nm diameter were successfully fabricated through a simple sonochemical route. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and room temperature photoluminescence (PL) characterizations were performed to investigate the morphological and structural properties of the obtained nanostructures. It has been shown that the synthesized cauliflower-like ZnO nanostructures irradiated UV luminescence and a green peak in visible band. Ultrasonic post-treatment of the particles for about 2 h increased the density of surface defects resulted in an increase in the green emission intensity. 相似文献
45.
Choi MJ Chandra G Lee HW Hou X Choi WJ Phan K Jacobson KA Jeong LS 《Organic & biomolecular chemistry》2011,9(20):6955-6962
The stereoselective synthesis of truncated 3'-aminocarbanucleosides 4a-d via a stereo- and regioselective conversion of a diol 9 to bromoacetate 11a and their binding affinity towards the human A(3) adenosine receptor are described. 相似文献
46.
MLN4924 (1), which is in clinical trials as an anticancer agent, was stereoselectively synthesized from d-ribose via a route involving stereoselective reduction, regioselective cleavage of an isopropylidene moiety, and selective displacement of a cyclic sulfate moiety as key steps. 相似文献
47.
We report a new helicoidal long-period grating by twisting a photonic crystal fiber under CO2 laser irradiation and experimentally investigated its novel transmission characteristics. The fabricated helicoidal PCF-LPG has a relatively short length of ∼1.4 cm with a low polarization dependent loss less than 1 dB and thermal shift of ∼3.7 pm/°C. The proposed device endows the unique resonant peaks tuning capability more than ∼18 nm by applying torsion stress, which has not been achieved in prior PCF-LPGs. From these novel thermo-optic and photo-mechanical properties, the proposed device can be applied for various components, including optical filters, attenuators, and sensors. 相似文献
48.
Mahsa Pourmirz Shahla Ebrahimnezh Ali Ramazani Aidin Bahrami Sholeh. Alaei Ali. Reza Dadrass 《无机化学学报》2019,35(2):344-350
通过2-溴-1-(对甲苯基)乙醛与三(对甲苯基)膦的反应制备α-磷配体:1-(对甲苯基)-2-(三对甲苯基-5-亚磷酰基)乙醛(L)。氯化镉和溴化汞与L分别反应,生成配合物[Cd(L)Cl2]2(C1)和[Hg(L)(μ2-Br)Br]2(C2)。用IR和NMR(1H,13C,31P)对配合物进行了表征。通过单晶X射线衍射测定了C2的结构,并在B3LYP/6-31G*水平对C2的结构进行了DFT计算研究,以揭示C2的复合反应位点与Schiff碱等亲核基团的相互作用。 相似文献
49.
E. Kuzmann L. Sziráki S. Stichleutner Z. Homonnay G. B. Lak M. El-Sharif C. U. Chisholm 《Hyperfine Interactions》2017,238(1):97
Constant current electrochemical deposition technique was used to obtain quaternary alloys of Sn-Fe-Co-Ni from a gluconate electrolyte, which to date have not been reported in the literature. For the characterization of electroplated alloys, 57Fe and 119Sn Conversion Electron Mössbauer Spectroscopy (CEMS), XRD and SEM/EDAX were used. XRD revealed the amorphous character of the novel Sn-Fe-Co-Ni electrodeposited alloys. 57Fe Mössbauer spectrum of quaternary deposit with composition of 37.0 at% Sn, 38.8 at% Fe, 16.8 at% Co and 7.4 at% Ni displayed a magnetically split sextet (B = 28.9T) with broad lines typical of iron bearing ferromagnetic amorphous alloys. Magnetically split 119Sn spectra reflecting a transferred hyperfine field (B = 2.3T) were also observed. New quaternary Sn-Fe-Co-Ni alloys were successfully prepared. 相似文献
50.
Mahsa Pourmirza Shahla Ebrahimnezhad Ali Ramazani Aidin Bahrami Sholeh.Alaei Ali.Reza Dadrass 《无机化学学报》2019,(2)
通过2-溴-1-(对甲苯基)乙醛与三(对甲苯基)膦的反应制备α-磷配体:1-(对甲苯基)-2-(三对甲苯基-5-亚磷酰基)乙醛(L)。氯化镉和溴化汞与L分别反应,生成配合物[Cd(L)Cl_2]_2(C1)和[Hg(L)(μ_2-Br)Br]_2(C2)。用IR和NMR(~1H,~(13)C,~(31)P)对配合物进行了表征。通过单晶X射线衍射测定了C2的结构,并在B3LYP/6-31G~*水平对C2的结构进行了DFT计算研究,以揭示C2的复合反应位点与Schiff碱等亲核基团的相互作用。 相似文献