Synthesis of 3-amino-5-nitrobenzaldehyde oxime and its conversion into 3,4-bis(3-amino-5-nitrophenyl)furoxan and isomeric 3(4)-(3-amino-5-nitrophenyl)-4(3)-nitrofuroxans

The oxime of the hitherto unknown 3-amino-5-nitrobenzaldehyde was synthesized by the reaction of 3-amino-5-nitrobenzaldehyde phenylhydrazone with excess of (NH₂OH)₂·H₂SO₄. The oxime obtained was used as the starting compound for the synthesis of novel diaryl- and arylnitrofuroxans. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2232–2235, December, 1997.     

Synthesis of 6,7-disubstituted-5H-pyrrolo[2,3-b]pyrazines via palladium-catalyzed heteroannulation

A concise and efficient method for the preparation of 6,7-disubstituted-5H-pyrrolo[2,3-b]pyrazines via a palladium-catalyzed heteroannulation is reported. Both conventional and microwave heating were used to perform the reactions, with the latter showing dramatically improved results.     

Synthesis, structural characterization and ferrimagnetic property of MnPS3 intercalated with nickel(II) cyclopolyamine complex cations

Two new intercalation compounds were prepared by the reactions of Ni(II) cyclopolyamine complex cations with a preintercalate Mn_1−xPS₃K_2x(H₂O)_y, respectively, through “ion exchange” process. Their structures were characterized by elemental analysis, X-ray powder diffraction and infrared spectroscopy. The lattice spacing increased 0.567 and 1.093 nm with respect to the pristine MnPS₃. Ferrimagnetism of the intercalates was confirmed by SQUID experiment with T_c at 40 and 33 K, respectively.     

Captodative olefins: methyl 2-aryloxy-3-dimethyl-aminopropenoates and their application in a new synthesis of benzofurans

The β-substituted captodative olefins methyl 2-aryloxy-3-dimethylaminopropenoates 4a-h were synthesized, via aminomethylenation of the corresponding 2-phenoxyacetic esters 9a-h. Lewis acid promoted intramolecular cyclization of alkenes 4 led to benzofurans 7a-h, in an efficient synthetic approach to the benzofuran frame.     

KF-Al2O3催化下二-γ-吡喃并[2,3-a;2'''',3''''-f]萘衍生物的合成

以芳醛、氰乙酸酯和1,5-萘二酚为原料,以乙醇为溶剂,在80℃以KF/Al2O3为催化剂合成了一系列的2,8-二氨基-4,10-二芳基-4H,10H-二-γ-吡喃并[2,3-a;2',3'-f]萘-3,9-二羧酸酯衍生物,该反应具有反应条件温和、产率良好、操作方便等优点.产物的结构通过IR,1HNMR和元素分析表征,并进一步通过X射线衍射分析确证4h的结构.     

Synthesis and chelation properties of new polymeric ligand derived from 8-hydroxy-5-azoquinoline hydroxy benzene

8-Hydroxy-5-azoquinoline phenyl methacrylate-formaldehyde (8H5AQPMA-F) macromonomer was prepared from methacryloyl chloride with condensation products of 8-hydroxy-5-azoquinoline phenol-formaldehyde, and polymerized in DMF at 70 °C using benzoyl peroxide as free radical initiator. Poly(8H5AQPMA-F) was characterized by infrared and nuclear magnetic resonance spectroscopic techniques. Polychelates were obtained when the DMF solution of the resin containing few drops of ammonia was treated with the aqueous solution of Cu(II)/Ni(II). Elemental analysis of the polychelates indicates that the metal to ligand ratio was about 1:2. The IR spectra of polychelates suggest that the metals were coordinated through the oxygen of the phenolic-OH group and nitrogen of the quinoline ligand. The DRS and magnetic moment data indicate a square planar for Cu(II) complex whereas octahedral for Ni(II) complex. The TGA data revealed the thermal stability of the resin and the polychelates. X-ray diffraction study revealed the incorporation of the metal ions significantly enhanced the degree of crystallinity. The sorption properties of the chelate-forming resin towards various divalent metal ions [Cu(II) and Ni(II)] were studied as a function of pH and electrolyte.     

Stereoselective routes to substituted β-amino carbonyl compounds via heterodiene [4π+2π] cycloadditions of auxiliary-based C2 symmetric ketene acetals

Heterodiene [4π+2π] cycloadditions of (S,S)-4,5-diaryl-2-methylene-1,3-dioxolanes 1 to a series of β-amido-α,β-unsaturated carbonyl compounds are diastereoselective (d.r.≥4:1). The products can be purified by trituration or crystallisation and hydrolysed with acid to generate the corresponding β-amido carbonyl compounds, the overall sequence effecting an auxiliary-based enantioselective conjugate addition of an acetate enolate, leading to β-aminoacid derivatives.     

Unexpected 1,2,3-triazole formation in the reaction of diethylaluminum azide with α′-amino-α,β-unsaturated ketones

4-Acyl-1H-1,2,3-triazoles are formed from diethylaluminum azide and α′-(N,N-dibenzylamino)-α,β-unsaturated ketones by [3+2] cycloaddition of azide, followed by 1,5 hydride transfer to the β carbon of the triazoline side chain and fragmentation of the tertiary amino group promoted by coordination of the latter to the Lewis acid. The structure of a triazole product is confirmed by X-ray crystallography.     

常见饮料中痕量铝的分光光度法研究

新试剂5-溴水杨基荧光酮可在pH5.5～6.8的六次甲基四胺缓冲溶液中,与铝,溴化十六烷基吡啶形成稳定的红色三元配合物。最大吸收波长约为568nm,摩尔吸光系数高达1.7×10~5L mol~(-1)·cm~1,常见金属离子很少干扰。据此,建立了测定微量铝的方法。其线性范围为0～6μg/25ml回收率在96％～103％之间。本文测定了常见饮茶,饮料及饮水中的微量铝。     

Effect of N2O pretreatment on fresh and regenerated Pd-Ag/α-Al2O3 catalysts during selective hydrogenation of acetylene

N₂O pretreatment has shown to result in enhancement of the performance of fresh commercial Pd-Ag/α-Al₂O₃ catalyst during selective acetylene hydrogenation. However, it showed no effect for the used and regenerated catalysts probably due to changes int he metal arrangement on the catalyst surface after regeneration.