芳香取代反应—ipso取代反应

谈到芳香取代反应,人们立刻会想到芳环上取代基的o~-、p-、m~-位上氢原子的取代反应。然而对另一类反应,即环上取代基本身的取代反应却少为人知。它是起始于试剂对芳环上取代基所在位置(ipso位)的进攻,进而置换了该取代基的反应。称作ipso取代反应。某些研究表明,试剂对氢原子所在位置的进攻与它对ipso位的进攻处于竞争状态,往     

芳香取代的几种新方法

本文介绍了芳香取代的几种新方法及其在有机合成中的应用。主要包括：（１）Ｖｉｃａｒｉｏｕｓ亲核取代，（２）邻位金属化定向反应，（３）钯催化的取代方法等。     

海藻酸-壳聚糖-海藻酸离子取代凝胶离子的取代性能

研究了海藻酸 壳聚糖 海藻酸 (alginate chitosan alginate ,ACA)离子取代凝胶对二价离子的取代性能。与传统离子交换树脂比较 ,ACA的离子取代速率比传统离子交换树脂快得多。ACA对二价金属离子的取代顺序是 :Pb2 + >Cu2 + >Ca2 + ≈Zn2 + ,其中 ,对Pb2 + 的选择性要大大高于Ca2 + ,其选择性系数是 316。ACA离子取代凝胶具有较快的离子取代速率和较高的吸附选择性 ,这使它有望成为一种新型的血液吸附剂用于临床金属中毒治疗。     

多取代吡啶类化合物的合成及生物活性

多取代吡啶类化合物的合成及生物活性;多取代吡啶;合成;生物活性     

含氟二芳基取代乙炔的合成

含氟二芳基取代乙炔的合成;ZnCl2/SiO2;含氟芳基取代乙炔;合成     

取代金刚烷的异构体计数

采用图论方法对单一种取代基取代的金刚烷和烷基取代的金刚烷构型、手性构型和非手性构型数进行了计算,结果分别以母函数形式和表格形式给出。     

单取代苯乙醛及其二氢吡啶衍生物的合成

以单取代苯乙酸为原料,在SOCl2/MeOH中制得甲酯;用NaBH4/MeOH将其还原制得取代苯乙醇;再用戴斯-马丁氧化剂氧化制得单取代苯乙醛;最后通过Hantzsch反应合成了9个1,4-二氢吡啶衍生物——2,6-二甲基-3,5-二乙氧羰基-4-取代苄基-1,4-二氢吡啶(4a～4i),其结构经1H NMR,13C NMR和MS表征,其中4b～4i为新化合物。     

高取代度玉米醋酸酯淀粉的制备与表征

高取代度玉米醋酸酯淀粉的制备与表征;取代度;醋酸酯淀粉;玻璃化转变温度;结晶度     

用N－取代三氯乙酰胺合成不对称取代脲

以无机碱作催化剂，用三氯乙酰苯胺与不同的胺反应，合成了８种不对称取代脲。     

海藻酸-壳聚糖-海藻酸凝胶离子取代机理

研究了海藻酸-壳聚糖-海藻酸(ACA)凝胶的离子取代机理.光学显微镜照相法证实ACA离子取代过程中溶胶-凝胶相界面的存在.动边界模型描述ACA离子取代凝胶对二价离子的取代动力学过程,结果表明,模型可靠.离子取代凝胶对二价离子的取代属于颗粒扩散控制机理.与离子交换树脂比较,ACA离子取代速率要快得多,ACA离子取代过程不同于传统离子交换树脂离子交换过程,它是金属离子在溶胶凝胶相转移过程中的取代过程;ACA是一种崭新的离子移变凝胶型离子吸附剂.     

取代螺环戊烷的电子轰击和化学电离正,负离子质谱

本文报道了苯取代螺环戊烷衍生物的电子轰击(EI)正离子和化学电离正、负离子(PNCI)质谱。通过亚稳离子测定,研究了该类化合物的裂解机理。在卤代螺环戊烷的EI质谱中,分子离子峰都很弱,甚至不出现M 离子。其特征离子为[M-X]~ 、[M-2X] 和[M-X-HX]~ 。CI正离子谱有较强的[M H]~ 、[M-2X]~ 和[M-x]~ ,CI负离子谱的特征离子为[M X]~-,它们在多数情况下为基峰离子,另外还出现HX_2~-或X~-离子。     

Skeletal Rearrangement of Substituted Benzaldoxime 3- (2,2-Dichlorovinyl)-2,2-dimethyl Cycle-propane Carboxylates under EI-MS

Introduction Substituted benzaldoxime 3-( 2, 2-dichlorovinyl )-2,2-dimethyl cyclopropanecarboxylates,considered as pyrethroid analogs, show a good bioactivity such as fungicidal, herbicidal and plantgrowth regulating activities[1,2]. EI-MS spectra of those compounds show the rearrangement of their structures, which has prompted us to elucidate their behavior under EI conditions. All the compounds studied have M-165 and M-99 fragment ions in the EI-MS spectra, but there is no segment with the mass of 165 and 99 lost directly from the molecular ions. So we postulated the process of rearrangement, it involved the cleavage of the C2C3 bond in the substituted cyclopropyl accompanied by the migration of disubstitued methylene-amino moiety to C2 or C3 position and elimination of a conjugated group with the mass of 165 or 99 to afford the even electron ion, of which the important step is the cleavage of the N-O bond. Although the cleavage of the alkoxy bond in the pyrethroids[3-5] has been reported, there has been no rearrangement reported. In order to test our postulations, MIKES and EI-HR-MS were carried out to elucidate the fragmentation pathways. The substituents in the phenyl ring played important roles in the stabilization of the product ions. The focal point of our work was to investigate two pathways of the skeletal rearrangement and the effect of the substituents.     

O-乙基-O-(取代γ-丁内酯基-α-次甲基N-烷基(或N,N-二烷基)硫代磷酰胺酯类化合物的合成

硫代磷酰胺酯类化合物在农药领域中有广泛的应用,为了寻找高效低毒的新药剂,人们改变了各种取代基团,其中研究数量最多的为有机磷杂环酯类和取代苯基酯类,但将内酯环结构引入这类化合物中的工作还未见文献报道,出于一些本身含有内酯环结构的天然产物杀菌剂存在于植物体内使植物具有抗病性,因此,本文参考一般内酯和硫代磷酰胺酯的合     

Photobehavior of (alpha-diimine)dimesitylplatinum(II) complexes

The photobehavior of complexes of the type Pt(diimine)(mes)2 is investigated (where diimine = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmp), 2,9-dimethyl-1,10-phenanthroline (2,9-dmp), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp), and 4,7-diphenyl-1,10-phenanthroline (dpp) and mes = the mesityl (2,4,6-trimethylphenyl) anion). For all compounds studied, solution RT emission is observed to be weak and excited-state lifetimes are found to be short (< or = 20 ns) regardless of solvent choice. Evidence is presented for energy-transfer quenching of Pt(dpp)(mes)2 luminescence in toluene by dissolved O2 (primarily producing singlet oxygen) with an observed quenching rate constant of kq > or = 1.3 x 10(9) M-1 s-1. Electron-transfer quenching is also observed in the presence of 3,5-dinitrobenzonitrile, yielding a quenching rate constant of kq > or = 1.6 x 10(9) M-1 s-1. The latter observation suggests that phase Pt(II) systems may have future value as excited-state reductants. All of the complexes display a much more intense and longer-lived luminescence in the solid state at room temperature. Several possible explanations for this dependence on phase are proposed, with the most probable mechanism involving radiationless deactivation in solution via rotation of the o-methyl groups of the mesityl ligands.     

Synthesis and Herbicidal Activity of [(Substituted Phenoxyacetoxy) (Substituted Phenyl)Methyl](Methyl) Phosphinates Containing Fluorine

Abstract

A series of [(substituted phenoxyacetoxy)(substituted phenyl)methyl](methyl)phos- phinates containing fluorine were designed and synthesized. All the synthesized compounds were identified by elemental analysis, IR, ¹H NMR, mass spectrometry. O-methyl [(2-fluorophenoxyacetoxy)(2,4-dichlorophenyl)methyl](methyl)phosphinate was further analyzed by X-ray single-crystal diffraction. Their herbicidal activity against a set of weed species was examined. Some of the compounds showed potential herbicidal activity, which provided some indications for further studies on structure modification.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

N-取代苯基-卤代邻羟基苄胺的合成、表征及抑菌活性

通过卤代水杨醛与取代芳胺缩合、NaBH4还原, 合成了15种N-取代苯基-卤代邻羟基苄胺化合物, 其中14种未见报道. 化合物的结构经IR, 1H NMR, MS与元素分析表征确证. 抑菌测试表明, 在质量浓度为0.05%时, 化合物对白色念珠菌的抑菌率高达100%, 具有强抑菌活性, 对金黄色葡萄球菌、大肠杆菌有一定的抑菌活性. 该类化合物对不同菌株的抑菌活性具有明显的选择性和特异性, 是一类极具潜力的抗真菌化合物. 构效分析表明, 胺基苯环上取代基的类型对化合物抑菌活性有重要影响, 引入F, Cl等卤原子, 能显著增强化合物的抑菌活性, 而引入NO2, OCH3等强吸、供电基团, 能显著降低其抑菌活性; 邻羟基苯环上引入卤原子的类型和数量对化合物抑菌活性有一定影响, 5-溴代化合物比5-氯代化合物、3,5-二溴代化合物对大肠杆菌的抑菌活性更高.     

2-(取代氨基硫代甲酰基)-3,4,5,6-四氢嘧啶的合成

以N,N'-二取代二硫代草酰胺与1,3-丙二胺在DMSO中进行缩合反应, 合成了一系列2-取代氨基硫代甲酰 基-3,4,5,6-四氢嘧啶, 反应在2 h内完成, 产率56%～76%. 产物结构经元素分析, IR, ¹H NMR及MS确证.     

Obituary: Professor Frank M. Leslie FRS (1935-2000)

The synthesis of five new cholesteryl-based monomers (M-1?M-5) and the corresponding smectic comb-like polymers containing cholesteryl groups (P-1?P-5) is presented. The chemical structures were characterised by FT-IR, 1H NMR and elemental analyses. The specific optical rotations were evaluated with a polarimeter. The phase behaviour was investigated by polarising optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The specific optical rotation values of these monomers and polymers with the same number of phenyl rings and terminal groups were nearly equal; however, they decreased with increasing the aryl numbers in the mesogenic core. The monomers M-1?M-5 showed oily streak and focal conic optical textures, or finger print textures characteristic of the chiral nematic phase. The polymers P-1?P-5 showed the smectic A phase. The melting, clearing, and glass transition temperatures increased, and the mesophase temperature ranges widened with increasing the aryl number in the mesogenic core. However, although the molecular structures of M-4 and M-5 were similar to those of M-3, namely their mesogenic cores contained three phenyl rings, their phase behaviour differed considerably, and T _m and T _i of M-4 and M-5 were less than those of M-3. In addition, M-4 and M-5 showed a clear glass transition similar to the polymer. Furthermore, the ester linkage bond and aryl arrangement in the mesogenic core also affected the phase behaviour.     

(S)-萘普生-1,4-二氢吡啶类化合物的合成与生物活性

以(S)-萘普生为原料制得的(S)-萘普生氯甲酯与1,4-二氢吡啶-3,5-二羧酸单酯在无水K₂CO₃存在下于DMF中反应得到的粗产品经梯度结晶或柱层析纯化得标题化合物. 合成的7种目标化合物收率21%～73%, 经¹H NMR, IR, MS确证了结构. 家兔离体血管平滑肌收缩试验研究表明, 大部分目标化合物对苯肾上腺素诱导的血管收缩有松弛作用.     

Substituted imidazole complexes of platinum(IV) halides

Platinum(IV) halides formed complexes of the type PtL₂X₄ [L=1-vinyl imidazole (1,-VIm), 1-methylimidazole (1-MeIm), 1,2-dimethylimidazole (1,2-Me₂Im), 1-vinyl-2-methylimidazole (1-V-2-MeIm), 2-methylimidazole (2-MeIm), 2-ethylimidazole (2-EtIm), 2-isopropylimidazole (2-i-PrIm), and 4-methylimidazole (4-MeIm); X=Cl, Br] in neutral aqueous solution. The 1-n-butylimidazole (1-n-BuIm) ligand yielded only (LH)₂PtX₆ compound in the same medium. The compounds were characterised by elemental analyses, IR, UV-VIS and ¹HNMR spectra.