Copper-Catalyzed Domino Annulation Approaches to the Synthesis of Benzoxazoles under Microwave-Accelerated and Conventional Thermal Conditions
作者:Russell D. Viirre、Ghotas Evindar、Robert A. Batey
DOI:10.1021/jo702145d
日期:2008.5.1
Two domino annulation approaches for benzoxazole synthesis have been developed. In the first approach, copper-catalyzed intermolecular cross-coupling of 1,2-dihaloarenes with primary amides initially forms the Ar−N bond of the benzoxazole ring, followed by copper-catalyzed intramolecular cyclization to form the Ar−O bond. Benzoxazoles were formed in good yields for the reaction of 1,2-dibromobenzene
已经开发了两种用于苯并恶唑合成的多米诺环化方法。在第一种方法中,铜催化的1,2-二卤代芳烃与伯酰胺的分子间交叉偶联最初形成苯并恶唑环的Ar-N键,然后进行铜催化的分子内环化形成Ar-O键。苯并恶唑以高产率形成,用于1,2-二溴苯的反应,但该反应对3,4-二溴甲苯的反应没有区域选择性。此外,该方法受到1,2-二卤代芳烃的可用性的限制。由于这些局限性,开发了另一种更通用的单锅多米诺环化策略,该策略涉及在Cs 2 CO 3存在下2-溴苯胺与酰氯的反应。,催化CuI和不可酰化的配体1,10-菲咯啉。在这些条件下,先将苯胺酰化,然后进行铜催化的分子内环化反应,生成2-卤代苯胺,形成苯并恶唑环的Ar-O键。与常规加热相比,使用微波辐射的优化条件获得的反应时间短得多(即210°C持续15分钟,而95°C持续24 h),并被用于合成小型苯并恶唑库。这些铜催化的方法补充了苯并恶唑合成的现有策略,该策略通常利用2-氨基苯酚作为前体。
Lawesson’s Reagent and Microwaves: A New Efficient Access to Benzoxazoles and Benzothiazoles from Carboxylic Acids under Solvent-Free Conditions
Lawesson'sreagent acts as an efficient promoter in the solvent-free microwave-assisted synthesis of 2-substituted benzoxazoles from carboxylic acids and 2-aminophenol, and thus, constitutes a general synthetic method for these compounds. This new application of Lawesson'sreagent is valid also for benzothiazoles with very high efficiency level. A variety of aromatic, heteroaromatic and aliphatic carboxylic
Iron-Catalyzed C–H Alkylation of Heterocyclic C–H Bonds
作者:Kaki Raveendra Babu、Nengbo Zhu、Hongli Bao
DOI:10.1021/acs.orglett.6b03287
日期:2017.1.6
An efficient, iron-catalyzed C–H alkylation of benzothiazoles by using alkyl diacyl peroxides and alkyl tert-butyl peresters which are readily accessible from carboxylic acids to synthesize 2-alkylbenzothiazoles is developed. This reaction is environmentally benign and compatible with a broad range of functional groups. Various primary, secondary, and tertiary alkyl groups can be efficiently incorporated
Copper-catalysed intramolecular O-arylation: a simple and efficient method for benzoxazole synthesis
作者:Fengtian Wu、Jie Zhang、Qianbing Wei、Ping Liu、Jianwei Xie、Haojie Jiang、Bin Dai
DOI:10.1039/c4ob02068e
日期:——
An efficient protocol has been developed for the copper-catalysed intramolecular cyclization of N-(2-iodo-/bromo-/chloro-phenyl)benzamides for the synthesis of 2-substituted benzoxazoles.
Ligand-promoted, copper nanoparticles catalyzed one-pot synthesis of substituted benzoxazoles from 2-bromoanilines and acyl chlorides
作者:Yong Wang、Chaolong Wu、Shoujie Nie、Dingjian Xu、Min Yu、Xiaoquan Yao
DOI:10.1016/j.tetlet.2015.10.078
日期:2015.12
A facile, highly efficient, and practical one-pot synthetic strategy for benzoxazoles was developed by using copper nanoparticles as a catalyst with o-bromoanilines and acyl chlorides as starting materials. With the promotion of 1,10-phenanthroline ligand, the copper nanoparticles catalyst showed highly catalytic activity under mild conditions. This methodology is tolerant of a wide variety of functional groups and gives good to excellent yields in most examples. Furthermore, the solid catalyst could be recovered and reused conveniently several times with satisfactory yields. (C) 2015 Elsevier Ltd. All rights reserved.