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31.
Fan‐Pin Lee Yu‐Chang Chen Jih‐Jung Chen Ian‐Lih Tsai Ih‐Sheng Chen 《Helvetica chimica acta》2004,87(2):463-468
Two new cyclobutanoid amides, piperarborenine A (=1,1′‐{[(1α,2α,3β,4β)‐2,4‐bis(3,4‐dimethoxyphenyl)cyclobutane‐1,3‐diyl]dicarbonyl}bis[5,6‐dihydropyridin‐2(1H)‐one]; 1 ) and piperarborenine B (=1,1′‐{[(1α,2α,3β,4β)‐2‐(3,4‐dimethoxyphenyl)‐4‐(3,4,5‐trimethoxyphenyl)cyclobutane‐1,3‐diyl]dicarbonyl}bis[5,6‐dihydropyridin‐2(1H)‐one]; 2 ) were isolated from the stem of Piper arborescens, besides two known cyclobutanoid amides, piperarboresine (=1,1′‐{[(1α,2α,3β,4β)‐2‐(7‐methoxy‐1,3‐benzodioxol‐5‐yl)‐4‐(3,4,5‐trimethoxyphenyl)cyclobutane‐1,3‐diyl]dicarbonyl}bis[5,6‐dihydropyridin‐2(1H)‐one]; 3 ) and piplartine‐dimer A (=1,1′‐{[(1α,2α,3β,4β)‐2,4‐bis(3,4,5‐trimethoxyphenyl)cyclobutane‐1,3‐diyl]dicarbonyl}bis[5,6‐dihydropyridin‐2(1H)‐one]; 4 ). The structures of the two new compounds were determined by spectral analyses. 相似文献
32.
Fang-Yuan Lee Yu-Ju Chen Gene-Hsiang Lee Jih Ru Hwu 《Journal of organometallic chemistry》2005,690(2):441-449
The reaction of Os3(CO)12 with an excess of 1-hydroxypyridine-2-thione and Me3NO gives three mononuclear osmium complexes Os(CO)2(η2-SC5H4N(O))2 (1), Os(CO)2(η2-SC5H4N(O))(η2-SC5H4N) (2), and Os(CO)2(η2-SC5H4N)2 (3). The results of single-crystal X-ray analyses reveal that complex 1 contains two O,S-chelate pyridine-2-thione N-oxide (PyOS) ligands, whereas complex 2 contains one O,S-chelate PyOS and one N,S-chelate pyridine-2-thiolate group. The unique structure of 2 provides evidence of the pathway for this transformation. When this reaction was monitored by 1H NMR spectroscopy the triosmium complexes Os3(CO)10(μ-H)(μ-η1-S-C5H4N(O)) (4) and Os3(CO)9(μ-H)(μ-η1:η2-SC5H4N(O)) (5) were identified as intermediates in the formation of the mononuclear final products 1-3. The proposed pathway is further supported by the observation of several dinuclear osmium intermediates by electrospray ionization mass spectrometry. In addition, the reaction of Os3(CO)12 with 1-hydroxypyridine-2-thione in the absence of Me3NO at 90 °C generated mononuclear complex 2 as the major product along with smaller amounts of complexes 1 and 3. These results suggest that the N-oxide facilitates the decarbonylation reaction. Crystal data for 1: monoclinic, space group C2/c, a = 26.9990(5) Å, b = 7.6230(7) Å, c = 14.2980(13) Å, β = 101.620(2)°, V = 2882.4(4) Å3, Z = 8. Crystal data for 2: monoclinic, space group C2/c, a = 5.7884(3) Å, b = 13.9667(7) Å, c = 17.2575(9) Å, β = 96.686(1)°, V = 1385.69(12) Å3, Z = 4. 相似文献
33.
Chia‐I Yen Szu‐Mam Liu Wei‐Shang Lo Jhe‐Wei Wu Yi‐Hsin Liu Prof. Rong‐Jie Chein Prof. Renqiang Yang Prof. Kevin C.‐W. Wu Prof. Jih Ru Hwu Prof. Nianhan Ma Prof. Fa‐Kuen Shieh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2925-2929
Using a simple method, the aldehyde groups of zeolitic imidazolate framework‐90 (ZIF‐90) nanocrystals were converted into carboxyl, amino, and thiol groups, without affecting the integrity of the framework. Notably, for the first time, correlations between functionality and cytotoxicity are also demonstrated via in vitro cytotoxicity assays. The positive charged aminated‐ZIF‐90 presumably results in either perturbation of cell membrane, more efficient cell uptake, or both. Therefore, the half‐maximal effective (EC50) concentration of aminated‐ZIF‐90 has a higher cytotoxicity of about 30 μg mL?1. 相似文献
34.
Condensation of carboxylic acids and alcohols to give esters was accomplished with selectivity under photolytic conditions in 66-99% yields by use of CCl4 or BrCCl3 at room temperature. 相似文献
35.
A local electrodeposition method was developed for chitosan by exploiting a pH gradient between a macroscopic electrode (the support) and a much smaller counter electrode. The deposition was confined either by using the direct mode of scanning electrochemical microscopy (SECM) or by performing the deposition in channels of a microfluidic network. The roughness was characterized by noncontact scanning force microscopy. The availability of amino groups at the surface of the microstructures was visualized after labeling by confocal laser scanning microscopy. The enzyme glucose oxidase could be entrapped during the electrochemical deposition and showed activity as seen by SECM images. 相似文献
36.
An efficient and convergent route for the synthesis of the natural product (+)-lithospermic acid, which possesses anti-HIV activity, was accomplished. The (±)-trans-dihydrobenzo[b]furan core therein was prepared by two different strategies. The first strategy involved the use of a palladium-catalyzed annulation to generate an appropriately substituted benzo[b]furan ester followed by a stereoselective reduction of a carbon-carbon double bond with Mg-HgCl(2)-MeOH. The second strategy relied on an aldol condensation between a suitably substituted methyl arylacetate and 3,4-dimethoxybenzaldehyde, followed by cyclization. Finally, a total synthesis of (+)-lithospermic acid was completed via coupling of a trans-dihydrobenzo[b]furan cinnamic acid with an enantiomerically pure methyl lactate. 相似文献
37.
Two series of oxime esters containing the 2,6-diazaanthracene-9,10-dione bis-(O-benzoyloxime) and 4,5-diazafluoren-9-one O-9-benzoyloxime moieties have been synthesized and tested as photo-induced DNA cleaving agents. All these compounds were found to cleave DNA upon irradiation with 312 nm UV light. The structure-activity relationship of these molecules for DNA cleavage was established. A plausible reaction mechanism is also proposed. 相似文献
38.
Jihène Ben Kraïem 《合成通讯》2013,43(1):110-117
2,4-Diketoesters 2 have first been reported as starting materials for the synthesis of a new class of α-hydroxymethyl-α,β-unsaturated ketones 3. Thus, under heterogeneous liquid–liquid medium in the presence of concentrated aqueous potassium carbonate as a base, both aliphatic and aromatic 2,4-dioxoalkanoates 2 react with aqueous formaldehyde to afford the corresponding ketones 3 in fair to good yields. 相似文献
39.
Jih‐Jung Chen Chang‐Yih Duh Hung‐Yi Huang Ih‐Sheng Chen 《Helvetica chimica acta》2003,86(6):2058-2064
A new pyridone alkaloid, 5,6‐dihydro‐5‐hydroxy‐1H‐pyridin‐2‐one ( 1 ), and a new ester, sintenin (=3‐(3,4‐dimethoxyphenyl)propyl 3‐(3,4‐dimethoxyphenyl)propanoate 2 ), together with three known compounds, 5,6‐dihydro‐1H‐pyridin‐2‐one ( 3 ), d‐sesamin (=5,5′‐(3a,4,6,6a‐tetrahydro‐1H,3H‐furo[3,4‐c]furan‐1,4‐diyl)bis[1,3‐benzodioxole]; 4 ), and (E)‐phytol (=3,7,11,15‐tetramethylhexadec‐2‐en‐1‐ol; 5 ) have been isolated from the whole plant of Piper sintenense. The structures of the two new compounds were determined through spectral analyses. Among twenty isolates obtained so far, four compounds exhibited effective cytotoxicities against P‐388, HT‐29, or A549 cell lines in vitro. 相似文献
40.
An effective chemical route to nanostructured tungsten oxide films derived from a peroxopolytungstic acid (PTA)/thiourea precursor solution is demonstrated. The conventional procedure of preparing the precursor needs more than 24 h for well‐mixing and refluxing the PTA‐based solution, while the thiourea‐assisted approach takes less than 1 h to prepare the precursor solution because the excess hydrogen peroxide can be efficiently eliminated by oxidation of thiourea. With the precursor solution, tungsten oxide films are deposited by spin coating followed by high temperature annealing. The film annealed at 400 °C possesses a porous nanostructure of nanocrystalline tungsten oxide embedded in an amorphous tungsten oxide matrix, which arises from the gaseous species released through decomposition of thiourea oxides during annealing. The 400 °C‐annealed, thiourea‐assisted tungsten oxide film exhibits electrochromic (EC) properties superior to those of the film prepared without thiourea, including large transmittance modulation and coloration efficiency, fast response time and adequate reliability. When increasing the annealing temperature to 450 °C, the thiourea‐assisted tungsten oxide film is also porous but well‐crystallized and shows inferior EC properties. Electrochemical impedance spectroscopy analysis indicates that, in addition to the porous structure, a fast charge‐transport rate within the solid portion of the 400 °C‐annealed nanostructured film plays a crucial role in enhancing EC performances of the thiourea‐assisted tungsten oxide film. 相似文献