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
Tosyl Hydrazine-Promoted Tandem Condensation and Cyclization of Acyl Azobenzenes Enabling Access to 2<i>H</i>
-Indazoles under Metal-Free Aerobic Conditions
作者:Jeong-Yu Son、Hyunseok Kim、Yonghyeon Baek、Kyusik Um、Gi Hoon Ko、Gi Uk Han、Sang Hoon Han、Kooyeon Lee、Phil Ho Lee
DOI:10.1002/adsc.201801055
日期:2018.11.16
Tosyl hydrazine‐promoted tandem condensation and cyclization of 2‐acyl azobenzenes under metal‐free aerobic conditions was demonstrated to give 2‐aryl‐2H‐indazoles having alkyl‐ or aryl groups at the 3‐position in quantitative yields through the release of water, molecular nitrogen, and sulfinic acid. All of the examples produced the corresponding 2H‐indazoles in quantitative yields. The present reaction
Direct Access to Acylated Azobenzenes via Pd-Catalyzed C–H Functionalization and Further Transformation into an Indazole Backbone
作者:Hongji Li、Pinhua Li、Lei Wang
DOI:10.1021/ol303434n
日期:2013.2.1
Azobenzenes were readily acylated at the 2-position through a Pd-catalyzed C-H functionalization from simple aromatic azo compounds and aldehydes in good yields. The obtained acylated azobenzenes could be efficiently converted into the corresponding indazole derivatives in nearly quantitative yields.