Rhodium(III)-Catalyzed Indazole Synthesis by C–H Bond Functionalization and Cyclative Capture
作者:Yajing Lian、Robert G. Bergman、Luke D. Lavis、Jonathan A. Ellman
DOI:10.1021/ja402761p
日期:2013.5.15
An efficient, one-step, and highly functional group-compatible synthesis of substituted N-aryl-2H-indazoles is reported via the rhodium(III)-catalyzed C-H bond addition of azobenzenes to aldehydes. The regioselective coupling of unsymmetrical azobenzenes was further demonstrated and led to the development of a new removable aryl group that allows for the preparation of indazoles without N-substitution. The 2-aryl-2H-indazole products also represent a new class of readily prepared fluorophores for which initial spectroscopic characterization has been performed.
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