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991.
Promoted by metallic cadmium allylilic and propargyl bromides react smoothly with aldehydes in aqueous DMF to give homoallylic and homopropargyl alcohols in moderate to good yields. It can also promote pinacol coupling of aromatic aldehydes. The metallic cadmium is produced in situ by the reduction of CdCl2 H2O with samarium metal. 相似文献
992.
The addition reaction process of Wang resin bound amines with isocyanates was monitored directly using a FTIR method. It showed that the reaction process was greatly enhanced under microwave irradiation. 相似文献
993.
Abstract The Sm/cat. CoCl2 or Sm/cat. &;Cl2 ? 6H2O system promoted disulfides to react with anhydrides or acyl chlorides to afford thiolesters in good yields under mild and neutral conditions. 相似文献
994.
The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in a reusable ionic liquid, ethylammonium nitrate, at room temperature in the absence of any catalyst with high yields. 相似文献
995.
Total synthesis of α-elvucitabine was achieved in 26% overall yield by a concise nine-step procedure starting from L-lyxose, with trimethylsilyl trifluoromethaneoulfonate (TMSOTf)–mediated stereocontrolled α-N-glycosidation and olefination through Barton–McCombie deoxygenation being the key steps, and the stereochemistry of the product was determined by nuclear Overhauser effect spectroscopy. 相似文献
996.
α-Functionalized 1-benzylbenzotriazoles (3, 4 and 12), derived from the lithiation of 1-(2,3-dimethoxybenzyl)benzotriazole 2 followed by reactions with electrophiles, or from the condensation of benzyl alcohol 11 with benzotriazole, undergo formal [3 + 2] cycloadditions with styrenes upon treatment with ZnBr2 to give functionalized indans (9, 10, 13 and 14). 相似文献
997.
2-Aminoarylketones undergo smooth condensation with α-methylene ketones in the presence of 10 mol% of poly(ethylene glycol) (PEG)–supported sulfonic acid under mild reaction conditions to afford the corresponding poly-substituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective, and environmentally benign. 相似文献
998.
A convenient one-pot synthesis of benzo[f]pyrimido[4,5-b]quinoline derivatives is described via three-component reaction of benzaldehydes, naphthalen-2-amine, and barbituric acid at room temperature in aqueous media catalyzed by iodine. Compared with other methods, this three-component reaction used a green solvent, gave good yields, and was operationally simple. 相似文献
999.
Bei‐Bei Zhang Qian Jiang Zhi‐Xin Liao Chao Liu Shi‐Jun Liu 《Helvetica chimica acta》2013,96(7):1281-1289
Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells. 相似文献
1000.
Qian-Li Zhang Ai-Jun Wang Zi-Yan Meng Ya-Hui Lu Hong-Jun Lin Jiu-Ju Feng 《Mikrochimica acta》2013,180(7-8):581-587
We have prepared porous and network-like nanofilms of gold by galvanic replacement of a layer of copper particles acting as a template. The films were first characterized by scanning electron microscopy and X-ray diffraction, and then modified with cysteamine so to enable the covalent immobilization of the enzyme microperoxidase-11. The immobilized enzyme undergoes direct electron transfer to the underlying electrodes, and the electrode displays high electrocatalytic activity towards the reduction of oxygen and hydrogen peroxide, respectively, owing to the largely enhanced electroactive surface of the porous gold film. The detection limit of H2O2 is 0.4 μM (3 S/N). Figure
In this work, porous network-like Au films were prepared by galvanic replacement using Cu film as a sacrificial template. The cysteamine modified Au film was used to immobilize microperoxidase-11, which showed good stability and excellent electrochemical performance towards the reduction of O2 and H2O2, respectively 相似文献