Rh(III)-Catalyzed Regio- and Chemoselective [4 + 1]-Annulation of Azoxy Compounds with Diazoesters for the Synthesis of 2<i>H</i>-Indazoles: Roles of the Azoxy Oxygen Atom
作者:Zhen Long、Zhigang Wang、Danni Zhou、Danyang Wan、Jingsong You
DOI:10.1021/acs.orglett.7b00631
日期:2017.6.2
tandem C–H alkylation/intramolecular decarboxylative cyclization of azoxy compounds with diazoesters for the synthesis of 3-acyl-2H-indazoles is disclosed. The azoxy instead of the azo group enables a distinct approach for cyclative capture, leading to a [4 + 1]-annulation rather than a classic [4 + 2] manner. The azoxy oxygen atom is traceless after annulation, and further removal from the product is
Azoxyarenes are among important scaffolds in organic molecules. Direct oxidativecoupling of primary anilines provides a concise fashion to construct them. However, whether these scaffolds can be prepared from secondary N-alkylanilines is not well explored. Here, we present a catalytic selective oxidativecoupling of secondary N-alkylaniline to afford azoxyarene with tungsten catalyst under mild conditions
report a new nitrogen-directed Rh(III)-catalyzed C(sp2)–H bond functionalization of N-nitrosoanilines and azoxybenzenes with maleimides as a coupling partner, in which the olefination/alkylation process can be finely controlled at room temperature by variation of the reaction conditions. This method shows excellent functional group tolerance, and presents a mild access to the resulting olefination/alkylation
Rh(III)-Catalyzed [4 + 1]-Annulation of Azoxy Compounds with Alkynes: A Regioselective Approach to 2<i>H</i>-Indazoles
作者:Zhen Long、Yudong Yang、Jingsong You
DOI:10.1021/acs.orglett.7b00982
日期:2017.6.2
A rhodium-catalyzed regioselective C–H activation/cyclization of azoxycompounds with alkynes has been disclosed to construct a variety of 2H-indazoles. A [4 + 1]-cycloaddition rather than a normal [4 + 2] mode is observed in the process of cyclative capture along with an oxygen-atom transfer and a C≡C triple bond cleavage. This protocol features a broad substrate scope, a good functional group tolerance
Zr(OH)
<sub>4</sub>
‐Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes
作者:Jiaheng Qin、Yu Long、Fangkun Sun、Pan‐Pan Zhou、Wei David Wang、Nan Luo、Jiantai Ma
DOI:10.1002/anie.202112907
日期:2022.1.10
Zr(OH)4 can catalyze the selective oxidation of anilines to azoxybenzenes, symmetric/unsymmetric azobenzenes and nitrosobenzenes for a wide range of substrates. Control experiments and DFT calculations reveal that the activation of H2O2 and O2 can be attributed to the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4, respectively.
Zr(OH) 4可以催化苯胺选择性氧化为偶氮苯、对称/不对称偶氮苯和亚硝基苯,适用于多种底物。对照实验和 DFT 计算表明,H 2 O 2和 O 2的活化可分别归因于 Zr(OH) 4的桥接羟基和末端羟基。