超酸硝化法合成1-甲基-3,4,5-三硝基吡唑

首次采用超酸对1-甲基吡唑(1)进行硝化合成了1-甲基-3,4,5-三硝基吡唑(MTNP),其结构经1H NMR,13C NMR,IR,MS和元素分析确证。在最佳反应条件[1 10 mmol,KNO3-发烟硫酸为硝化剂,n(1)∶n(KNO3)=1∶5,于130℃反应4 h]下,MTNP收率30.7%。     

三(4-硝基苯基)甲醇及其氯化物的合成与表征

以三苯甲烷为原料,经硝化、氧化和氯化三步反应合成了三(4-硝基苯基)甲烷(TNPM),三(4-硝基苯基)甲醇(TNPMO)和三(4-硝基苯基)氯甲烷(TNPMCl)等一系列三芳基甲烷类化合物.三苯甲烷经混酸硝化制备TNPM;然后经CrO3/冰醋酸氧化生成TNPMO,最后与乙酰氯反应得到TNPMCl.各步产物的结构经核磁共振与红外光谱进行了表征.     

运用NMR和DFT研究Michael加成反应的动力学行为及反应机理：(CO)5W=C(OEt)C2Ph作为底物

利用核磁共振方法研究了取代吡唑对炔基Fischer卡宾化合物的Michael加成的动力学行为，该反应为典型的二级反应。当吡唑的3，5-位由较大基团取代时，反应速率常数变小，而活化焓和活化熵明显增大。利用密度泛函理论研究了炔基钨卡宾为底物的Michael加成反应机理，发现吡唑上取代基团的增大可以导致第三步反应的活化能大于第一步，从而使反应的决速步骤由原来的第一步转变为第三步。     

1-甲基-3-丙基-4-氨基吡唑-5-甲腈的研究

以1-甲基-3-丙基吡唑-5-甲酸为原料,经酰化、脱水、硝化、还原反应合成了1-甲基-3-丙基-4-氨基吡唑-5-甲腈,然后与醛类缩合得到吡唑并嘧啶酮衍生物.在Pd/C催化氢化1-甲基-3-丙基-4-硝基吡唑-5-甲腈的过程中,利用HPLC和HPLC-HRMS分离检测到硝基还原为氨基过程的3个中间体:羟胺、氧化偶氮、偶氮化合物,提出了可能的还原机理.产物结构经~1H NMR,~(13)C NMR,IR和MS分析表征.     

微波辐射下磷酸改性铌酸催化的香豆素修饰吡唑并[3,4-b]吡啶衍生物的高效合成

香豆素和吡唑并[3,4-b]吡啶骨架广泛存在于具有生物活性的天然化合物中,在药物化学中也被广泛用作药物核心单元,具有极其重要的作用.以磷酸改性铌酸作为催化剂,通过微波辐射下醛、香豆素衍生物、5-氨基吡唑的三组分反应一锅法高产率地合成一系列香豆素修饰的吡唑并[3,4-b]吡啶衍生物.该反应一步完成,具有催化剂和溶剂对环境友好,操作简单等优点.产物的结构经红外光谱、核磁共振谱及高分辨质谱予以确定.     

由邻苯二甲酸二乙酯制备水合茚三酮的反应机理探讨

以邻苯二甲酸二乙酯为原料,经Claisen酯缩合反应、酸性酯水解反应、热脱羧反应、亚硝化反应、脱肟反应、羰基还原反应、Aldol反应、邻二醇氧化裂解反应制备了水合茚三酮,对各步的反应机理进行了详细的讨论。     

1,3-交替构象杯[4]芳烃-香豆素衍生物的合成

以对叔丁基杯[4]芳烃为原料,通过醚化、原位硝化、还原、缩合四步反应合成了三个新型的具有1,3-交替构象的杯芳烃-香豆素衍生物,其结构经1H NMR,13C NMR,IR和MS表征.     

串联式三组分反应构建取代吡唑杂环

建立一种串联三组分反应构建取代吡唑杂环的方法.以肼和醛为原料在二氯乙烷中反应先生成腙3,直接加入丙炔酸甲酯(4),在氯化亚铜催化下快速生成Michael加成产物5.该中间体以化学量的三氯化铁氧化发生环合反应,获得高收率的吡唑环衍生物6.各步反应中间体不必分离,脂肪肼、芳香肼以及芳香醛对该反应具有良好适应性.     

替卡格雷的合成工艺改进

以丙二酸二乙酯和硫脲为起始原料,经环合、取代、硝化及还原等9步反应合成了替卡格雷,总收率20.9%,其结构经1H NMR和HR-ESI-MS确证。     

新型联苯四氮唑沙坦类化合物的合成

以3-甲基-4-硝基苯甲酸为原料,经酯化、还原、硝化等10步反应合成了4个新型的联苯四氮唑沙坦类化合物,其结构经1H NMR,13C NMR和MS表征。     

硝基苯的制备及废硫酸回收利用的研究

苯在四氯化碳溶剂中以硝酸和疏酸的混合酸为硝化剂在温和条件下进行硝化，硝基苯的产率高，硫酸可以回收再利用。例如，在带有搅拌器、滴液漏斗、温度计和冷凝器的四颈烧瓶中，加入４４．４毫升苯和４０毫升四氯化碳，将３９．５毫升浓硝酸和４１．５毫升浓硫酸混合后从滴液漏斗中滴加，维持温度在１５～５５℃之间，约４０分钟滴完后，在５５～６２℃继续反应３０分钟。有机层分别用水、１０％氢氧化钠溶液、水洗涤，干燥、蒸馏，先蒸出溶剂可再用。然后收集２０４～２１０．８℃的馏份，得硝基苯６０．６克，产率９８．５３％。废硫酸通过蒸馏浓缩后，可重新用于硝化反应。     

谷胱甘肽和Ebselen对胰岛素硝化的抑制及其相互作用机理的研究

生物体内NO和超氧阴离子快速反应生成的过氧亚硝酸根离子(ONOO^-，peroxynitrite)是一种强细胞毒性物质，它诱导蛋白质酪氨酸残基硝化是其损伤生物系统的重要途径之一。为了探讨谷胱甘肽和ebselen对胰岛素硝化的抑制及其相互作用机理，采用UV-Vis、HPLC和ESI-MS等方法，研究了ONOO^-对胰岛素的硝化作用、小分子抗氧化剂谷胱甘肽(GSH)和ebselen对ONOO^-硝化胰岛素的影响以及它们之间的相互作用。结果表明单独的GSH和ebselen对ONOO^--引发的胰岛素硝化均有明显的抑制，而作为谷胱甘肽过氧化物酶(GPx)的底物GSH 与GPx的模型化合物ebselen之间存在相互拮抗作用，经过对其产物分析，确定其机理是GSH和ebselen能够直接反应生成一种加合物，从而抑制了GSH和ebselen各自的抗硝化能力。     

NO(2)(+) nitration mechanism of aromatic compounds: electrophilic vs charge-transfer process

The nitration of methylnaphthalenes with NO(2)BF(4) and NOBF(4) was examined in order to shed light on the controversial aromatic nitration mechanism, electrophilic vs charge-transfer process. The NO(2)(+) nitration of 1,8-dimethylnaphthalene showed a drastic regioselectivity change depending on the reaction temperature, where ortho-regioselectivity at -78 degrees C and para-regioselectivity at 0 degrees C were considered to reflect the electrophilic and the direct or alternative charge-transfer process, respectively, because the NO(+) nitration through the same reaction intermediates as in the NO(2)(+) nitration via a charge-transfer process resulted in para-regioselectivity regardless of the reaction temperature. The NO(2)(+) nitration of redox potential methylnaphthalenes higher than 1,8-dimethylnaphthalene gave a similar ortho-regioselectivity enhancement to 1,8-dimethylnaphthalene at lower temperature, thus reflecting the electrophilic process. On the other hand, the NO(2)(+) nitration of redox potential methylnaphthalenes lower than 1,8-dimethylnaphthalene showed para-regioselectivity similar to the NO(+) nitration, indicating the direct or alternative charge-transfer process. In the presence of strong acids where the direct charge-transfer process will be suppressed by protonation, the ortho-regioselectivity enhancement was observed in the NO(2)(+) nitration of 1,8-dimethylnaphthalene, suggesting that the direct charge-transfer process could be the main process to show para-regioselectivity. These experimental results imply that the NO(2)(+) nitration proceeds via not only electrophilic but also direct charge-transfer processes, which has been considered to be unlikely because of the high energy demanding process of a bond coordination change between NO(2)(+) and NO(2). Theoretical studies at the MP2/6-31G(d) level predicted ortho- and para-regioselectivity for the NO(2)(+) nitration via electrophilic and charge-transfer processes, respectively, and the preference of the direct charge-transfer process over the alternative one, which support the experimental conclusion     

6-氯-2(1 H)-喹喔酮合成方法的改进

设计了以对氯苯胺和氯乙酰氯为原料,经缩合、硝化、还原、环合、氧化五步制得6-氯-2(1H)-喹喔酮的位置选择性合成方法,并对以氯乙酰氯作为苯胺的氨基保护试剂进行硝化的反应和对含活泼氯的硝基化合物进行还原的反应进行了研究.研究结果表明以氯乙酰氯作为苯胺的氨基保护试剂进行硝化的反应符合一般的硝化定位规则,而含活泼氯的硝基化合物的还原在优化条件下以铁粉为还原剂可以高选择性获得目标产物.     

Practical neutral aromatic nitration with nitrogen dioxide in the presence of heterogeneous catalysts under moderate oxygen pressure

A practical neutral aromatic nitration process using nitrogen dioxide in the presence of FeCl₃ · 6H₂O under 40–100 psig of oxygen was developed, and nitration of several aromatic compounds, including the deactivated nitrobenzene, was performed in a successful manner. The correlation of reaction rate with equivalents nitrogen dioxide, oxygen pressure, amount of catalyst and temperature was investigated through the nitration of benzene. Following the optimization of reaction conditions, the nitration of benzene was scaled up to 476 mol. Furthermore, inorganic solid catalysts with pore size over 5 Å and surface area over 100 m²/g were applied to newly developed neutral nitration.     

Scavengers for peroxynitrite: inhibition of tyrosine nitration and oxidation with tryptamine derivatives, alpha-lipoic acid and synthetic compounds

The inhibitory effects of various endogenous and synthetic compounds on the nitration and oxidation of L-tyrosine by peroxynitrite were examined. Nitrating and oxidizing activities were monitored by the formation of 3-nitrotyrosine and dityrosine with a HPLC-UV-fluorescence detector system, respectively. Glutathione, serotonin and synthetic sulfur- and selenium-containing compounds inhibited both the nitration and oxidation reaction of L-tyrosine effectively. However, 5-methoxytryptamine, melatonin and alpha-lipoic acid only inhibited the nitration reaction, and enhanced the formation of an oxidation product. This is important evidence that there are different intermediates in the nitrating and oxidizing reactions of L-tyrosine by peroxynitrite. It was suggested that 5-methoxytryptamine, melatonin and alpha-lipoic acid reacted only with the nitrating intermediate of peroxynitrite and inhibited nitration of L-tyrosine. Actually, the DNA strand breakage, which is believed to be a typical reaction of hydroxyl radical-like species, caused by peroxynitrite was not effectively inhibited by 5-methoxytryptamine. 5-Methoxytryptamine, melatonin and alpha-lipoic acid were viewed as useful reagents for investigating the mechanisms of damage by peroxynitrite in vitro.     

Highly efficient nitration of phenolic compounds in solid phase or solution using Bi(NO3)3.5H2O as nitrating reagent

[reaction: see text] Bi(NO(3))(3).5H(2)O was used as an efficient nitrating reagent in the nitration of phenolic compounds to give nitrated phenols in good to high yields. The nitration reaction proceeded smoothly by grinding 1 equiv of phenol, 2-methylphenol, 4-methylphenol, or 4-chlorophenol and Bi(NO(3))(3).5H(2)O, and the nitration of other phenolic compounds could be performed in acetone at ambient temperature (22-30 degrees C).     

硝酸铁对水杨酸甲酯的硝化及位置选择性

用硝酸铁对水杨酸甲酯硝化合成了3-硝基水杨酸甲酯和5-硝基水杨酸甲酯。 考察了反应时间、反应物配比、反应溶液酸碱性对产物收率和位置选择性的影响。 得出较好的反应条件为：反应时间3 h,n(硝酸铁)∶n(水杨酸甲酯)=2∶3。 少量硝酸有利于硝基化反应,且优先生成5-硝基水杨酸甲酯,而碱性不利于硝基化反应,且优先生成3-硝基水杨酸甲酯。 用量化计算解释了硝化反应的位置选择性机理。     

6-硝基胡椒酸的合成

胡椒醛经硝化,氧化,合成了6-硝基胡椒酸。其结构经UV,IR和MS确认,总收率44％。     

Study of Nitration of Hyperbranched Polyglycidols

Russian Journal of Applied Chemistry - The nitration of hyperbranched polyglycidols was studied. It was confirmed that there is no destruction of the polymeric chain when the nitration reaction is...