Palladium-Catalyzed Decarboxylative Couplings of 2-(2-Azaaryl)acetates with Aryl Halides and Triflates
作者:Rui Shang、Zhi-Wei Yang、Yan Wang、Song-Lin Zhang、Lei Liu
DOI:10.1021/ja107103b
日期:2010.10.20
Pd-catalyzed decarboxylative cross-couplings of 2-(2-azaaryl)acetates with arylhalides and triflates have been discovered. This reaction is potentially useful for the synthesis of some functionalized pyridines, quinolines, pyrazines, benzoxazoles, and benzothiazoles. Theoretical analysis shows that the nitrogen atom at the 2-position of the heteroaromatics directly coordinates to Pd(II) in the decarboxylation
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.
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
Synthesis of 2-benzyl benzoxazoles and benzothiazoles <i>via</i> elemental sulfur promoted cyclization of styrenes with 2-nitrophenols and <i>N</i>,<i>N</i>-dialkyl-3-nitroanilines
作者:Truong K. Chau、Nguyen T. Ho、Tuan H. Ho、Anh T. Nguyen、Khoa D. Nguyen、Nam T. S. Phan、Ha V. Le、Tung T. Nguyen
DOI:10.1039/d3ob01775c
日期:——
Annulation of 2-nitrophenols and N,N-dialkyl-3-nitroanilines with styrenes in the presence of elemental sulfur and the base DABCO successfully yielded 2-benzyl benzoxazoles and 2-benzyl benzothiazoles, respectively.