Kinetics and Mechanism of Reaction between N-Polyfluorophenylcarbonimidoyl Dichlorides and Tertiary Amines in Acetonitrile

The reaction of N-polyfluorophenylcarbonimidoyl dichlorides with tertiary amines in acetonitrile afforded chloroamidines R²NC(Cl) = NAr_F and alkyl chloride. The precursor of the products is the corresponding quaternary ammonium salt [R³N+C(Cl) = NAr_F]-Cl^-. The rate of the salt formation is described by a second order equation; however with some amines a saturation effect was observed for the reaction rate with the growing amine concentration. This fact and also the influence of the amine and the substrate structure on the reaction rate suggests that reaction proceeds by addition-elimination mechanism with formation of a tetrahedral intermediate. The latter in the rate-limiting stage undergoes a stereomutation into an intermediate of a configuration favorable for conversion into a quaternary salt.     

Photoredox Catalyzed Dealkylative Aromatic Halogen Substitution with Tertiary Amines

A reaction of aromatic halides bearing electron-withdrawing groups with tertiary amines in the presence of an iridium catalyst under blue light irradiation is described. Products of the aromatic substitution of the halide by the dialkylamino fragment are obtained. The interaction of aryl radicals with tertiary amines to generate zwitterionic radical species is believed to be the key factor responsible for the reaction efficiency.     

吡啶基有机碱催化O-羧基酐的活性开环聚合

O-羧基酐(OCA)是α-羟基酸与三光气的缩合产物, 其侧基结构丰富, 可开环聚合生成结构多样的聚α-羟基酸, 弥补了聚乳酸结构和性能单一的缺陷. 在OCA开环聚合过程中, 手性α-H容易发生外消旋化, 导致聚合物的立构规整度下降. 本文发现了一种结构简单的高性能有机催化剂—4-甲氧基吡啶, 其可在温和的条件下快速催化OCA的活性开环聚合, 有效抑制酯交换和手性α-H的外消旋化副反应, 合成出高立构规整度的窄分布聚α-羟基酸. 进一步研究发现, 虽然在甲苯和四氢呋喃等常见溶剂中, OCA的开环聚合遵循一级动力学, 但在环氧烷烃溶剂中, OCA开环聚合遵循零级动力学, 聚合反应速率与单体浓度无关. 作为新型高效有机碱催化剂, 4-甲氧基吡啶在多嵌段可降解聚酯高效合成和聚酯生物医药载体制备等方面具有潜在的应用价值.     

Chemoselective Reduction of Tertiary Amides to Amines Catalyzed by Triphenylborane

Triphenylborane (BPh₃) was found to catalyze the reduction of tertiary amides with hydrosilanes to give amines under mild condition with high chemoselectivity in the presence of ketones, esters, and imines. N,N‐Dimethylacrylamide was reduced to provide the α‐silyl amide. Preliminary studies indicate that the hydrosilylation catalyzed by BPh₃ may be mechanistically different from that catalyzed by the more electrophilic B(C₆F₅)₃.     

树状分子胺催化的Henry反应研究

Hemry反应是一类重要的构筑碳碳键的原子经济型反应,生成的双官能团化合物β-硝基醇是一种应用很广的有机合成中间体.以苯甲醛与硝基甲烷的Henry反应为模型,首先尝试了一些小分子弱碱催化剂的催化效果.在此基础上,合成了0～2代聚苯醚型树状分子哌啶催化剂,并进行了1H NMR,IR和MS表征,将其应用于Henry反应,对其催化性能进行了初步研究,结果表明:低代数树状分子哌啶在硝基甲烷中的催化效果较好,高代数树状分子哌啶表现出负的树状分子效应.     

The Reaction of Electron-Deficient Cyclopropane Derivatives with Aromatic Amines

Abstract

N-Aryl-trans,trans-α-carboxyl-β-benzoyl-γ-aryl-γ-butyrolactams were synthesized in high yields with high stereoselectivity by the reaction of electron-deficient cyclopropane derivatives, cis-1-benzoyl-2-aryl-6,6-dimethyl-5,7-dioxo-spiro-[2 (a) Zhang , J. ; Blazecka , P. G. ; Davidson , J. G. First direct reductive amination of mucochloric acid: A simple and efficient method for preparing highly functionalized α,β-unsaturated γ-butyrolactams . Org. Lett. 2003 , 5 , 553 – 556 ; (b) Sarma, K. D.; Zhang, J.; Curran, T. T. Novel synthons from mucochloric acid: The first use of α,β-dichloro-γ-butenolides and γ-butyrolactams for direct vinylogous aldol addition. J. Org. Chem. 2007, 72, 3311–3318 . [Google Scholar] 5 (a) Chen , Y. L. ; Ding , W. Y. A simple approach to highly stereoselective synthesis of β γ-trans-γ-butyrolactones . Chem. J. Chin. Univ. 1998 , 19 , 1614 – 1616 ; (b) Chen, Y. L.; Ding, W. Y.; Cao, W. G.; Lu, C. Stereoselective synthesis of N-aryl-trans,trans-α-carboxyl-β-methoxycarbonyl-γ-aryl-γ-butyrolactones. Synth. Commun. 2002, 32, 1953–1960.  [Google Scholar]]-4,8-octadiones, with aromatic amines. The reaction mechanism was proposed.     

Stereoselective Synthesis of Tertiary Allylic Amines by Titanium-Catalyzed Hydroaminoalkylation of Alkynes with Tertiary Amines

Intermolecular hydroaminoalkylation reactions of symmetrical and unsymmetrical alkynes with tertiary amines take place in the presence of catalytic amounts of TiBn₄, Ph₃C[B(C₆F₅)₄], and a sterically demanding aminopyridinato ligand precursor. The resulting products, synthetically and pharmaceutically useful tertiary β,γ-disubstituted allylic amines, are formed in convincing yields and with excellent stereoselectivity. Particularly promising for future applications is the fact that even the industrial side product trimethylamine can be used as a substrate.     

光催化氧化还原体系中硝酮与芳香叔胺的自由基偶联反应

通过氮α-位碳自由基构造氮α-位碳-碳键是合成含氮有机化合物的重要方法. 近期, 利用可见光催化氧化芳香叔胺—氮α-位去质子化形成氮α-位碳自由基的原理发展了一系列新颖的自由基加成(偶联)反应, 成为氮α-位碳自由基化学发展的重要方向. 本文应用Ir-催化剂, 实现了光催化氧化还原体系中硝酮与芳香叔胺的自由基偶联反应, 高效地合成β-氨基羟胺化合物. 该反应条件温和、操作简单, 具有较高的原子经济性, 且对于各种链状、环状以及手性硝酮都具有良好的适用性, 产物可方便地转化为重要的邻二胺化合物.     

胺及其衍生物的非酰基化动力学拆分

光学纯胺在合成与药物化学领域都有着广泛的应用,发展其高效的合成方法一直以来是有机化学界的研究热点.其中通过N酰基化及去酰基化动力学拆分方法获得光学纯胺化合物,已经成为合成手性胺类化合物的重要方法.近年来,基于非酰基化(或去酰基化)的不对称反应实现外消旋胺的动力学拆分的报道不断涌现,包括一些氨基不参与反应的非酰基化(或去酰基化)不对称反应的外消旋胺的动力学拆分.根据氮原子是否参与反应以及反应类型的不同,总结了外消旋胺的化学催化动力学拆分的研究进展.     

氨基酸衍生物催化的不对称Reformastky反应

首次使用侧链上带有配位基因的氨基酸组成的线二肽、环二肽及氨基酸酯作手性配体催化不对称的Reformatsky反应。考察了配体结构、反应底物结构以及反应条件等因素对反应产物ee值的影响。同其它两类配体相比,环肽具有更好的不对称催化效果,其中具有C2对称性的环肽3a效果最好,产物的ee值达到了64％。     

无溶剂体系酪氨酸酶催化对位苯酚类化合物与芳香胺的反应研究

以对苄氧基苯酚，对苄基苯酚和对苯氧基苯酚作为底物，研究在无溶剂体系下，酪氨酸酶分别催化它们与邻氨基苯甲醚的反应。考察了在无溶剂体系下，以底物200μmol为当量，酶催化该类反应的最适水含量为30～35μL，加酶量为35～40mg，反应时间为24h，以此为反应条件酶促催化合成了2和3b，3a，产率30～50％，并讨论了反应机制。     

Pyridine Scaffolds,Phenols and Derivatives of Azo Moiety: Current Therapeutic Perspectives

Synthetic heterocyclic compounds have incredible potential against different diseases; pyridines, phenolic compounds and the derivatives of azo moiety have shown excellent antimicrobial, antiviral, antidiabetic, anti-melanogenic, anti-ulcer, anticancer, anti-mycobacterial, anti-inflammatory, DNA binding and chemosensing activities. In the present review, the above-mentioned activities of the nitrogen-containing heterocyclic compounds (pyridines), hydroxyl (phenols) and azo derivatives are discussed with reference to the minimum inhibitory concentration and structure–activity relationship, which clearly indicate that the presence of nitrogen in the phenyl ring; in addition, the hydroxyl substituent and the incorporation of a diazo group is crucial for the improved efficacies of the compounds in probing different diseases. The comparison was made with the reported drugs and new synthetic derivatives that showed recent therapeutic perspectives made in the last five years.     

Efficient Acetylation of Alcohols,Phenols, and Amines Catalyzed by Melamine Trisulfonic Acid (MTSA)

Melamine trisulfonic acid (MTSA) was easily prepared by the reaction of melamine with neat chlorosulfonic acid at room temperature. This reagent can be used as an efficient catalyst for the acetylation of alcohols, phenols, and amines with Ac₂O under mild and completely heterogeneous reaction conditions.     

Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.     

Highly Efficient Michael Addition Reaction of Amines Catalyzed by Silica-Supported Aluminum Chloride

Aliphatic and aromatic amines undergo smooth nucleophilic addition to α,β-unsaturated compounds in the presence of a catalytic amount of silica-supported aluminum chloride at 60 °C and under solvent-free conditions to produce the corresponding β-amino compounds in excellent yields. This method is simple and convenient and works efficiently under mild conditions. This catalyst can used again without losing its activity three times.     

Electron Capture Gas Chromatography of Tertiary Amines After a Demethylation Reaction to Secondary Amines

Abstract

A gas chromatographic method for the determination of tertiary amines in micro- and nanogram amounts is presented. The tertiary amine is reacted with ethyl chloroformate to form a urethan, which is cleaved to a secondary amine. This is transformed to heptafluoro-butyramide, which makes quantitative determination with electron capture detection possible. The yields of the secondary amines for two tertiary amines were 60 and 75%. By use of internal standard technique in the entire reaction recoveries of 97.6 ± 2.2% at the 100 μg level and 100 ± 4% at the 200 ng level were obtained.