Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
作者:Xiaoyu Geng、Congyang Wang
DOI:10.1021/acs.orglett.5b00938
日期:2015.5.15
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C–H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh-
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.