可见光催化和电化学合成在咪唑并[1,2-a]吡啶3位碳-杂键构建中的应用

咪唑并[1,2-a]吡啶是一类独特的含氮化合物,该类衍生物在农药、生物医药和光电材料等领域具有重要作用.近年来,合成功能性的咪唑并[1,2-a]吡啶已经成为有机化学家和药物化学家研究的热点,并且取得了巨大进展.其中,基于绿色化学导向的可见光催化和电催化合成官能化的咪唑并[1,2-a]吡啶,已经成为合成该类化合物的强有力的工具.根据构建咪唑并[1,2-a]吡啶3位碳-杂键类型的不同,概述了近5年来可见光催化和电化学合成构建咪唑并[1,2-a]吡啶3位碳-杂键的相关研究.     

碘-二甲基亚砜促进新型四环噻唑并[3',2':2,3]吡啶并[4,5-d]吡啶并[1,2-a]嘧啶酮类衍生物的合成（英文）

介绍了在碘-二甲基亚砜(I_2-DMSO)促进作用下,通过Pictet-Spengler反应合成噻唑并[3',2':2,3]吡啶并[4,5-d]吡啶并[1,2-a]嘧啶酮(5)衍生物的合成方法.该反应的关键中间体2-(3-氨基-5-苯氨基噻唑-2-基)-4H-吡啶[1,2-a]嘧啶-4-酮(3),由2-氯甲基-4H-吡啶[1,2-a]嘧啶-4-酮(1)与N-苯基-N'-氰基-咪唑硫代碳酸钾(2)通过Thorpe-Ziegler异构化反应制得.该合成方法反应条件温和,操作简单,收率高.     

在含水介质中钯高效催化咪唑并[1,2-a]吡啶类化合物与芳基氯代物的碳氢芳基化反应（英文）

3-芳基咪唑并[1,2-a]吡啶骨架广泛存在于药物结构中,在药物学方面具有重要的地位及在材料化学、有机化学等方面也具有潜在的应用价值.在含水介质中,利用醋酸钯催化咪唑并[1,2-a]吡啶及其衍生物与芳基/杂芳基氯代物的碳氢芳基化反应,简便、高效地合成系列3-芳基咪唑并[1,2-a]吡啶类化合物,并以较好至优秀的收率获得芳基化产品.该方法采用廉价易得的芳基/杂芳基氯代物和咪唑并[1,2-a]吡啶类化合物为偶联反应的底物,且底物的范围能够拓展至缺电子、富电子的芳基氯代物和杂芳基氯代物及多种基团取代的咪唑并[1,2-a]吡啶类化合物.     

温和条件下高效合成咪唑并杂环-肼类衍生物的三组分串联反应（英文）

为了合成咪唑[1,2-a]并吡啶-肼类衍生物,发展了一种以简单易得的甲酰甲基溴化物、2-氨基吡啶衍生物和偶氮二甲酸酯为原料的三分子串联反应的方法.该串联反应先生成咪唑[1,2-a]并吡啶,然后紧接着连续发生C(3)—H键肼基化反应,而不像传统的一步接一步反应的方法.该方法具有操作简单、反应条件温和(无需过渡金属且反应温度低等)以及底物适用性广的特点.实验结果表明,带有给电子取代基的甲酰甲基溴化物和2-氨基吡啶衍生物有利于反应的进行,并以优秀的产率获得目标产物.     

无光敏剂参与的可见光诱导咪唑并[1,2-a]吡啶的三氟甲基化反应(英文)

发展了一个无光敏剂参与的可见光促进的咪唑并[1,2-a]吡啶衍生物的三氟甲基化新反应.该反应利用本课题组此前发展的基于硫叶立德骨架的亲电三氟甲基化试剂作为三氟甲基自由基源,反应条件温和,底物普适性好,同时兼容常见的官能团.机理研究表明该反应可被自由基捕获剂阻断.对两个反应底物及它们的1∶1混合物的紫外-可见光吸收光谱进行了研究,研究表明三氟甲基化试剂与咪唑并[1,2-a]吡啶之间形成了一个Donor-Acceptor加合物.在此基础上提出了一个合理的机理,即该加合物在光照条件下被激发,发生硫-三氟甲基键均裂生成三氟甲基自由基,该自由基与咪唑并[1,2-a]吡啶发生自由基取代反应.同时也成功地将该方法应用于治疗胃溃疡药物佐利米定的三氟甲基化衍生物的合成.     

咪唑并[1,2-a]吡啶C-3位C—H官能团化研究进展

3-取代咪唑并[1,2-a]吡啶类化合物是一类重要的含氮稠环化合物,在医药、材料等领域具有广泛的应用价值.C-3位C—H官能团化是构建3-取代咪唑并[1,2-a]吡啶类化合物的简单有效方法.按咪唑并[1,2-a]吡啶C-3位的成键类型(C—C、C—S/Se、C—N/P)进行分类,主要介绍了近几年来咪唑并[1,2-a]吡啶等氮杂稠环化合物C-3位C—H官能团化反应进展,并对今后发展作出了展望.     

有机光催化在构建咪唑并[1,2-a]吡啶3-位C—C键中的研究

在含氮有机化合物中,咪唑并[1,2-a]吡啶广泛应用于光学、材料科学和有机金属学等领域中。此外,这种结构还具有抗病毒、抗菌、杀菌和抗炎等多种生物活性。通过有机光催化咪唑并[1,2-a]吡啶3-位C-H键官能化构建C-C键的方法,因条件温和、对环境绿色友好等优点,已经成为合成官能化有机分子的有力策略。综述了自2016年来,有机光催化咪唑并[1,2-a]吡啶3-位C-H键官能化为C-C键的相关研究。      

碘介导的2-氨基吡啶对α,β-不饱和酮的双胺化反应合成3-酰基和2-酰基咪唑并[1,2-a]吡啶（英文）

开发了一种以分子碘为氧化剂、无过渡金属参与的2-氨基吡啶对α,β-不饱和酮的双胺化反应.该方法不仅可以合成3-酰基咪唑并[1,2-a]吡啶,而且通过改变反应溶剂和底物2-氨基吡啶上的取代基还可以选择性地合成结构新颖的2-酰基咪唑并吡啶衍生物.     

新型苯并噻吩稠合吡啶并[1,2-a]嘧啶衍生物的合成及其抑菌活性

利用Thorpe-Ziegler反应,通过2-氯甲基-4H-吡啶并[1,2-a]嘧啶-4-酮与2-巯基苯甲腈的环化制得2-(3-氨基苯并噻吩-2-基)-4H-吡啶并[1,2-a]嘧啶酮,继而在氨基磺酸作用下,通过Pictet-Spengler反应,设计合成了新型苯并噻吩并[3',2':2,3]吡啶并[4,5-d]吡啶并[1,2-a]嘧啶衍生物.初步抑菌活性试验表明,当浓度为50 mg/L时,化合物5b对黄瓜灰霉病菌和小麦赤霉病菌的抑制率达96%以上,5f对油菜菌核病菌的抑制率为98%,5g和5i对烟草赤星病菌的抑制率达93%以上.     

咪唑并吡啶化合物的合成研究进展

咪唑并吡啶类化合物是一类非常重要的含氮稠杂环化合物, 在医药、农药和染料工业有着广泛的应用. 该类化合物由于其特定的生理活性以及和吲哚、氮杂吲哚等在结构上的类似性, 引起了人们广泛的兴趣. 常见的咪唑并吡啶类化合物有咪唑并[1,2-a]吡啶、咪唑并[1,5-a]吡啶、咪唑并[4,5-b]吡啶和咪唑并[4,5-c]吡啶等类型. 以咪唑并[1,2-a]吡啶和咪唑并[1,5-a]吡啶化合物为例, 阐述该类化合物近十年来的合成研究进展.     

Synthesis and biological activity of fluorinated 7-aryl-2-pyridyl-6,7-dihydro[1,2,4]triazolo[1,5-a][1,3,5]triazin-5-amines

In our lead finding program, 12 new fluorinated 7-aryl-2-pyridyl-6,7-dihydro[1,2,4]triazolo[1,5-a][1,3,5]triazin-5-amines were prepared via a practical three-step procedure starting from (iso)nicotinic hydrazides. The fluorine substituted aryl fragment was introduced in the last step through cyclocondensation of N-(3-pyridyl-1,2,4-triazol-5-yl)guanidines and fluoro/trifluoromethyl substituted benzaldehydes. The structures of the compounds were confirmed by ¹H and ¹³C NMR spectral data. The tautomeric preferences for the compounds were established using 2D NOESY experiments. The antiproliferative activity of the synthesized 1,2,4-triazolo[1,5-a][1,3,5]triazines was evaluated against breast, colon and lung cancer cell lines. The highest antiproliferative activity in the series was found for 2-(pyridine-3-yl)-7-(4-trifluoromethylphenyl)-6,7-dihydro[1,2,4]triazolo[1,5-a][1,3,5]triazin-5-amine. The lack of inhibitory activity against bovine dihydrofolate reductase (DHFR) indicated that the antiproliferative activity was realized via other mechanisms.     

The tetrazole–azide tautomerism of some nitrotetrazolo [1,5-a]pyridines studied by NMR, IR spectroscopy and molecular orbital calculations

The 6-nitro- and 8-nitro- groups in the tetrazolo[1,5-a]pyridine molecule exhibit completely different influences on the tetrazole–azide equilibrium. Introduction of the methyl-, nitro-, azido groups or a bromine atom in positions 5, 6, 7 or 8 of the nitrotetrazolopyridine produce changes in the equilibrium constants. Based on the IR spectra taken in the solid state, the tetrazole structure was assigned for almost all the compounds studied. Only one of them, 2,6-diazido-3-nitropyridine, exists in the diazido-form in the solid. The ¹H, ¹³C, ¹⁵N, and ¹⁷O NMR spectral parameters (coupling constants, chemical shifts) as well as ab initio molecular orbital calculations were used to describe the tetrazole–azide tautomerism in solutions. The differences in the NMR parameters between the neutral compound (6,8-dinitrotetrazolo[1,5-a]pyridine) and its σ-adducts are also included as data for distinguishing between both molecules.     

Flash vacuum thermolysis of acenaphtho[1,2-a]acenaphthylene. Thermal behaviour of a polycyclic aromatic hydrocarbon containing two abutting pentagons

FVT of acenaphtho[1,2-a]acenaphthylene (1) gave acenaphtho[1,2-e]acenaphthylene (2), cyclopenta[cd]perylene (3) and cyclopenta[rst]benzo[hi]chrysene (4). The formation of 3 and 4 indicates that, besides ring contraction/ring expansion of 1 giving 2, homolytic scission of a five-membered ring carbon---carbon single bond of 1 is an important competitive process.     

Reactions of some 2H-Chromenes and 2H-Thiochromenes with triazolinediones

Simple 2H-chromenes and 2H-thiochromenes form the [2+2]-adducts, tetrahydro[1]benzo(thio)pyrano[3,4-c] [1,2]diazeto[1,2-a][1,2,4]triazoles, with triazolinediones, whereas their 3- and 4-bromo and the corresponding cycloalkylamino derivatives undergo an overall etectrophilic substitution sequence.     

Synthesis of quaternary succinimides promoted by Ferric Nitrate

An efficient protocol has been accomplished for the synthesis of quaternary α-aminosuccinimides in toluene medium involving 2-phenylimidazo[1, 2-a]pyridine in a one-pot reaction promoted by Ferric Nitrate at 120?°C. The protocol presented herein, is for the first time, via a novel transformation where Ferric Nitrate promotes imidazo[1,2-a]pyridine structural metamorphosis to the title compound quaternary succinimides. High compatibility, easy work-up, and excellent yields are the advantages of this protocol. The quaternary α-aminosuccinimides are expected to have great potential in synthesizing quaternary α-amino acids and applications in medicinal chemistry.     

Tandem Approach to Functionalized Pyrrolo[3,4-α]carbazole-1,3-diones via a Pd-catalyzed Indole-to-carbazole Transformation

A one-pot and efficient tliree-component reaction of indoles, acrylates and maleimides for the synthesis of pyrrolo[3,4-α]carbazole-1,3-dione derivatives was developed. Three C-C bonds and one ring were created in a single step via an indole-to-carbazole transformation triggered by Pd(II)-catalyzed direct C3-alkenylation of indoles.     

Mild synthesis of enantiomerically pure imidazo-[1,2-a]azepines mediated by Yb(OTf)3

The reaction of various chiral 2,2′-diaryldialdehydes with achiral and chiral 1,2-diamines in the presence of Lewis acids to give imidazo[1,2-a]azepines was investigated. Best results were achieved with Yb(OTf)₃; the reaction outcome is strongly dependent upon the geometric features of both reactants. Kinetic resolution of rac-2,2′-dinaphthyldialdehyde with (R,R)-1,2-diphenyl-1,2-diamminoethane (up to 92% e.e.) was achieved.     

Convenient one-step synthesis of a medicinally relevant benzopyranopyridine system

Benzopyrano[2,3-b]pyridine is an important privileged medicinal scaffold. A three-component reaction of salicylaldehydes, thiols and 2 equiv of malononitrile that leads to the formation of a series of compounds incorporating 2,4-diamino-3-cyano-5-sulfanylbenzopyrano[2,3-b]pyridine framework is described. A proposed mechanism with the supporting experimental data is presented.     

过渡金属催化[2 + 2 + 2]环加成反应合成吡啶衍生物

环加成反应可以一步同时构建多个化学键,是目前国内外研究最为活跃的领域之一。相比于传统方法,过渡金属催化的[2+2+2]环加成反应是合成吡啶衍生物的有效手段。本文从反应机理、非手性吡啶化合物合成和手性吡啶化合物合成三个方面阐述了近年来吡啶衍生物的研究情况,涉及Co、Rh、Ru、Fe、Ni、Ti等金属催化体系。     

A Facile,Atom‐Economical,and One‐Pot Pseudo Four‐Component Synthesis of Isoxazolylspiro[diindeno[1,2‐b;2′,1′‐e]pyridine‐11,3′‐indoline]‐2′,10,12‐triones Catalyzed by pTSA

A facile, atom‐economical, and one‐pot pseudo four‐component method for the synthesis of isoxazolylspiro[diindeno[1,2‐b ;2′,1′‐e ]pyridine‐11,3′‐indoline]‐2′,10,12‐trione derivatives ( 14 ) is described. Prominent advantages of this new method are operational simplicity, excellent yields with high purity, short reaction time, easy workup, and mild conditions.