2-位官能团化合成2-取代苯并噻唑的研究进展

2-取代苯并噻唑类衍生物在化工、医药、农业等领域具有广泛的应用价值.2-位官能团化是合成2-取代苯并噻唑化合物的一种便捷、有效的合成方法.综述了苯并噻唑2-位的烷基化、酰基化、芳基化、胺基化以及磷酸化等产物的合成方法并进行了归类和分析,同时对其发展进行了展望.     

2-取代苯并噻唑类衍生物合成方法研究的新进展

2-取代苯并噻唑类衍生物在工业、农业、医药等领域有广泛的应用前景,因此这类衍生物合成的新方法备受关注.笔者以邻氨基苯硫酚、芳香邻氨基二硫化物、硫代酰胺、硫脲与邻卤苯胺等反应原料为基础,从引入硫原子的方法及反应机理的角度综述了近几年合成2-取代苯并噻唑类衍生物的新方法.     

6-取代苯并噻唑-2-氨基硫代磷酸二烷基酯的合成

用6-位取代的2-氨基苯并噻唑与三氯硫磷反应,合成了3个苯并噻唑-2-氨基硫代磷酰二氯,并由此合成了9个苯并噻唑-2-氨基硫代磷酸二烷基酯.讨论了苯并噻唑环上取代基对反应的影响和产物中硫代磷酸酯的烷基的空间效应对反应的影响.所合成的部分化合物对人喉鳞状细胞癌(Hep-2)具有一定的抑制能力.     

2-氨基苯并噻唑类化合物的合成研究进展

2-氨基苯并噻唑类化合物是一类极其重要的氮杂环化合物,在医药、农药等领域具有广阔的应用前景.鉴于这类化合物多样的生物活性,科研工作者们广泛关注并开发出很多新颖的合成方法.系统总结了 2-氨基苯并噻唑类化合物的合成方法,按照合成原料的不同对这些方法进行了归类和分析,并对其未来发展进行了展望.     

铜催化苯并噻唑与二芳基碘鎓盐的芳基化反应（英文）

二芳基碘盐具有毒性低、反应条件温和及选择性高的优点,在有机合成中一直受到关注,已被广泛用作芳基化试剂,可用于芳杂环化合物的交叉偶联反应和芳基化反应等.发展了一种铜催化下苯并噻唑与二芳基碘鎓盐反应合成2-芳基苯并噻唑衍生物的方法.该方法具有底物范围广泛、基团耐受性良好及产率高等优点.     

硒催化羰基化合成苯并噻唑-2-氨基甲酸酯

以非金属Se为催化剂,以CO替代剧毒光气及其复杂衍生物作羰基化试剂,以O2为氧化剂,经2-氨基苯并噻唑与醇发生"一锅法"的硒催化氧化羰基化反应,开辟了一条经济、绿色、简便、高效的合成苯并噻唑-2-氨基甲酸酯类化合物的新途径.研究了反应温度、压力、醇的用量及碱的种类等因素对生成苯并噻唑-2-氨基甲酸酯的影响,获得了实施该...     

高分子负载苯并噻唑鎓盐的制备及其催化反应

高分子负载试剂和催化剂在有机合成中已得到广泛应用.前文我们报道了苯并噻唑鎓盐催化合成1,4-二羰基化合物的反应,发现反应中鎓盐活性有衰减.张标宏等用20%交联聚苯乙烯负载 Stetter 催化剂曾获较好结果.本文拟报道高分子苯并噻唑鎓盐的制备及其催化反应.     

荧光素的全合成

设计了一条新的萤火虫荧光素(6)的全合成路线.以对甲氧基苯胺为起始原料,经酰胺化、硫代、水解、铁氰化钾氧化等反应构筑苯并噻唑环得到6-甲氧基苯并噻唑-2-甲酸(2).首次采用一锅法对2进行酰氯-酰胺化后,经脱水制得关键中间体2-氰基-6-甲氧基-苯并噻唑(4);4经脱甲基、与D-半胱氨酸盐酸水合物反应合成了6,总收率20%,100%ee.其结构经UV,1H NMR,FT-IR和MS表征.     

含苯并噻唑的硫脲嘧啶衍生物的合成及抗菌活性评价

2-氨基苯并噻唑衍生物和对氯甲基苯甲酰氯反应合成中间体N-(苯并[d]噻唑-2-基)-4-(氯甲基)苯甲酰胺(5),进一步与4-氧代-6-苯基-2-硫代-1,2,3,4-四氢嘧啶-5-腈(6)反应,合成了一系列未见报道的含苯并噻唑的硫脲嘧啶类化合物7.通过红外光谱、质谱、核磁共振谱和元素分析等方法对化合物进行了结构表征.测试了化合物7对解淀粉芽孢杆菌、金黄色葡萄球菌、枯草芽孢杆菌的抑菌活性. 24 h抑菌试验结果显示,部分化合物对供试的菌株具有较强的抑制活性.     

2-二氟溴甲基-1,3-苯并噻唑的简便合成

本文应用二氟溴乙酸作为二氟溴甲基的合成子,实现了2 巯基芳胺与二氟溴乙酸的缩合反应合成2-二氟溴甲基-1,3-苯并噻唑。该反应以5当量二氟溴乙酸,氯苯为溶剂,于100 ℃下与2-巯基芳胺反应18~40 h,产率高达88%。目标产物通过核磁共振和高分辨质谱表征。该反应条件温和,是对现有合成2-二氟溴甲基-1,3-苯并噻唑的良好补充。     

Synthetic Approaches to Biologically Active C-2-Substituted Benzothiazoles

Numerous benzothiazole derivatives are used in organic synthesis, in various industrial and consumer products, and in drugs, with a wide spectrum of biological activity. As the properties of the benzothiazole moiety are strongly affected by the nature and position of substitutions, in this review, covering the literature from 2016, we focus on C-2-substituted benzothiazoles, including the methods of their synthesis, structural modification, reaction mechanisms, and possible pharmacological activity. The synthetic approaches to these heterocycles include both traditional multistep reactions and one-pot atom economy processes using green chemistry principles and easily available reagents. Special attention is paid to the methods of the thiazole ring closure and chemical modification by the introduction of pharmacophore groups.     

Ru(III)-catalyzed oxidative reaction in ionic liquid: an efficient and practical route to 2-substituted benzothiazoles and their hybrids with pyrimidine nucleoside

An efficient, practical and environmentally benign synthesis of 2-substituted benzothiazoles was developed through RuCl₃-catalyzed oxidative condensation of 2-aminothiophenol with aldehyde in ionic liquid by using air as the oxidant. With this procedure, a series of 2-substituted benzothiazoles and benzothiazole/pyrimidine nucleoside hybrids with antimicrobial activities were efficiently prepared from easily accessible starting materials.     

Hypervalent iodine mediated intramolecular cyclization of thioformanilides: expeditious approach to 2-substituted benzothiazoles

A new, mild, and efficient method has been developed for the synthesis of 2-substituted benzothiazoles via the intramolecular cyclization of thioformanilides by using hypervalent iodine reagents in CH2Cl2 at ambient temperature. The reaction proceeds via a thiyl radical in high yields to give the novel compound oxybis benzothiazole and is also amenable to generating combinatorial libraries of heterocyclic compounds by solid-phase synthesis.     

Syntheses of 2-Aryl Benzothiazoles via Photocatalyzed Oxidative Condensation of Amines with 2-Aminothiophenol in the Presence of BODIPY Derivatives

A simple, convenient, and efficient new method for synthesis of 2-aryl benzothiazoles under mild conditions with nonmetal catalyst has been developed. Boron–dipyrromethene (BODIPY) dyes were used as photocatalysts for aerobic oxidative reactions of amine with 2-aminothiophenol. The approach will be very useful for the synthesis of benzothiazole derivatives and the development of photocatalytic reactions.     

Synthesis of some substituted imidazo [5, 1-b] benzothiazoles

Cyclization of formylated and acetylated -substituted 2-aminomethylbenzothiazoles with phosphorus oxychloride gives 3-substituted imidazo [5, 1-b] benzothiazoles, and 3-substituted 1-methylimidazo [5, 1-b] benzothiazoles. Treatment of 2-benzothiazolyl-4-pyridylaminomethane with formic acid gives 3-(4-pyridyl) imidazo [5, 1-b] benzothiazole. 1-Mercapto-3-phenylimidazo [5, 1-b] benzothiazole is converted into 3-phenylimidazo [5, 1-b] benzothiazole by elimination of the mercapto group.     

Abnormal Nucleophilic Substitution on Methoxytropone Derivatives: Steric Strategy to Synthesize 5-Substituted Azulenes

Azulene is a non-alternant non-benzenoid aromatic system, and in turn, it possesses unusual photophysical properties. Azulene-based conjugated systems have received increasing interest in recent years as optoelectronic materials. Despite the routes available for the preparation of substituted azulene derivatives, there remain few methods that allow regioselective substitution on the seven-membered ring of azulenes due to the subtle reactivity difference among the various positions. This report explores the reactivity of substituted tropolones as the azulene precursors and also provides a new method to create 5-substituted azulenes. The reaction of cyanoacetate enolate with unsubstituted 2-methoxytropone affords azulene through the attack of the nucleophile on the C-2 center (normal pathway). We have observed that 3-substituted 2-methoxytropones undergo steric-guided nucleophilic addition at the C-7 center (abnormal pathway) to afford 5-substituted azulene derivatives. Based on this observation and DFT calculation, a new synthetic strategy is devised for the regioselective synthesis of 5-substituted multifunctional azulenes, which cannot be accessed by any other method.     

High resolution mass spectrometry.—II Some substituted benzothiazoles

The mass spectra of nineteen substituted benzothiazoles have been recorded and the identity of the various ions in the mass spectra has been established by high resulution (accurate) mass measurement. Deuterium labelling has been used to elucidate the fragmentation processes of these compounds. The parent compound of the series, benzothiazole, exhibits the loss of hydrogen cyanide and carbon monosulphide from the parent ion as the most important decomposition pathways. The hydrogen atom concerned in the loss of hydrogen cyanide is shown to originate from the 2-position of benzothiazole, while in 2-substituted benzothiazoles, different mechanisms are apparent for the loss of hydrogen cyanide, and these are clarified by deuterium labelling. Some substituted benzothiazoles can lose sulphur from their molecular ions, a process which does not occur in benzothiazole itself. The substituted benzothiazoles undergo many other types of fragmentations, in some cases retaining the substituent, and in other cases losing it prior to collapse of the thiazole ring.     

Direct C–H amination of benzothiazoles by magnetically recyclable CuFe2O4 nanoparticles under ligand-free conditions

A simple and highly practical method for the synthesis of 2-N-substituted benzothiazoles has been developed by using nano copper ferrite as a magnetically separable, recyclable catalyst. The present tandem process allows to get access to a wide range of 2-N-substituted benzothiazoles in good to excellent yields by the reaction of benzothiazole with nitrogen nucleophiles in the presence of Cs₂CO₃ as a base. The nano CuFe₂O₄ could be recovered and reused with no significant loss of catalytic activity.     

A convenient synthesis of 2-acyl benzothiazoles/thiazoles from benzothiazole/thiazole and N,N'-carbonyldiimidazole activated carboxylic acids

A convenient and efficient strategy for the synthesis of 2-acyl benzothiazoles/thiazoles has been developed. The treatment of benzothiazole/thiazole with allylic Grignard reagents readily generates the corresponding 2-Grignard reagents, which is followed by a reaction with N,N'-carbonyldiimidazole activated carboxylic acids to afford various 2-acyl benzothiazoles/thiazoles products. The synthetic method is applicable to a wide array of carboxylic acids and allows easy access to 2-acyl benzothiazoles/thiazoles with considerable yields under mild reaction conditions.     

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives

The review is devoted to modern trends in the chemistry of 2-amino and 2-mercapto substituted benzothiazoles covering the literature since 2015. The reviewed heterocycles belong to biologically active and industrially demanded compounds. Newly developed synthesis methods can be divided into conventional multistep processes and one-pot, atom economy procedures, realized using green chemistry principles and simple reagents. The easy functionalization of the 2-NH₂ and 2-SH groups and the benzene ring of the benzothiazole moiety allows considering them as highly reactive building blocks for organic and organoelement synthesis, including the synthesis of pharmacologically active heterocycles. The review provides a summary of findings, which may be useful for developing new drugs and materials and new synthetic approaches and patterns of reactivity.