Direct α-Chalcogenation of Aliphatic Carboxylic Acid Equivalents
作者:Aniket Gupta、Ajijur Rahaman、Sukalyan Bhadra
DOI:10.1021/acs.orglett.9b02424
日期:2019.8.2
A novel approach to α-chalcogenation of aliphaticcarboxylicacids has been developed by means of transforming them as the corresponding benzazoles. The catalyst system, consisting of CuI, DMSO, and a base, operates through a unique mechanism to access a range of practically significant thio- and selenoethers that are otherwise challenging to achieve. The applicative potentials have been exemplified
通过将脂肪族羧酸转化为相应的苯唑类,开发了一种将脂肪族羧酸进行 α-硫属元素化的新方法。由 Cu I 、DMSO 和碱组成的催化剂体系通过独特的机制运行,以获取一系列具有实际意义的硫醚和硒醚,否则这些化合物难以实现。应用潜力已通过利用所得硫属化合物作为合成生物学相关分子和合成中间体的前体来举例说明。
Elemental Sulfur-Promoted Oxidative Rearranging Coupling between o-Aminophenols and Ketones: A Synthesis of 2-Alkyl benzoxazoles under Mild Conditions
作者:Thanh Binh Nguyen、Pascal Retailleau
DOI:10.1021/acs.orglett.7b01775
日期:2017.7.21
In the presence of N-methylpiperidine, elemental sulfur was found to act as excellent oxidant in promoting oxidative rearranging coupling between o-aminophenols and ketones. A wide range of 2-alkylbenzoxazoles was obtained under mild conditions.
Microwave-Assisted Direct Synthesis of 2-Substituted Benzoxazoles from Carboxylic Acids under Catalyst and Solvent-Free Conditions
作者:Asit K. Chakraborti、Raj Kumar、C. Selvam、Gurmeet Kaur
DOI:10.1055/s-2005-868509
日期:——
A direct coupling of carboxylic acids with 2-aminophenol under microwave irradiation has been achieved leading to the synthesis of 2-substituted benzoxazoles under metal and solvent-free conditions. Aliphatic, aromatic and heteroaromatic carboxylic acids provide good yields. Benzoxazole formation takes place in the presence of chloro, methoxy, phenoxy, thiophenoxy, and α,β-unsaturated functionalities. In the case of dicarboxylic acids, the reaction proceeds via the formation of the corresponding anhydride with predominant formation of the mono-benzoxazole.
Ag
<sup>I</sup>
‐Catalyzed Reaction of Enol Diazoacetates and Imino Ethers: Synthesis of Highly Functionalized Pyrroles
作者:Kuiyong Dong、Ahmad Humeidi、Wendell Griffith、Hadi Arman、Xinfang Xu、Michael P. Doyle
DOI:10.1002/anie.202101641
日期:2021.6.7
AgI-catalyzed efficient method for the coupling of imino ethers and enol diazoacetates through a [3+2]-cycloaddition/C−O bond cleavage/[1,5]-proton transfer cascade process is reported. The general class of imino ethers that includes oxazolines, benzoxazoles and benzimidates are applicable substrates for these reactions that provide direct access to fully substituted pyrroles with uniformly high chemo- and
报道了一种前所未有的 Ag I催化有效方法,用于通过 [3+2]-环加成/C-O 键裂解/[1,5]-质子转移级联过程偶联亚氨基醚和烯醇重氮乙酸酯。包括恶唑啉、苯并恶唑和苯甲亚胺酯在内的一般亚氨基醚类是这些反应的适用底物,可直接获得具有均匀高化学和区域选择性的完全取代的吡咯。吡咯 2-、5- 和 N-位取代的高度可变性表征了这种方法,该方法也提供了通过对所得 N-官能吡咯的轻松修饰来进一步实现吡咯多样化的切入点。
One-Pot Synthesis of 2-Substituted Benzoxazoles Directly from Carboxylic Acids
作者:Dinesh Kumar、Santosh Rudrawar、Asit K. Chakraborti
DOI:10.1071/ch08193
日期:——
Methanesulfonic acid has been found to be a highly effective catalyst for a convenient and one-pot synthesis of 2-substituted benzoxazoles by the reaction of 2-aminophenol with acid chlorides, generated in situ fromcarboxylicacids. Aryl, heteroaryl, and arylalkyl carboxylicacids provided excellent yields of the corresponding benzoxazoles. The reaction conditions were compatible with various substituents