Rh(III)-catalyzed annulation of azobenzenes and α-Cl ketones toward 3-acyl-2H-indazoles
作者:Huan Li、Yuxuan Han、Zi Yang、Zhenyu Yao、Lianhui Wang、Xiuling Cui
DOI:10.1016/j.cclet.2020.12.027
日期:2021.5
afforded in up to 97% yields for more than 30 examples. The obtained products are potentiallyvaluable in organic synthesis and drug discovery. This protocol featured with high efficiency, extensive functional group tolerance and mild reaction conditions. The one-step efficient construction of an anti-inflammatory agent confirms the practicability of this procedure.
Silver-catalyzed [3+2]-cycloaddition of benzynes with diazocarbonyl species via a postulated (1H-indazol-1-yl)silver intermediate
作者:Chiou-Dong Wang、Rai-Shung Liu
DOI:10.1039/c2ob26760h
日期:——
We reported a new synthesis of 2-aryl-2H-indazoles via a silver-catalyzed [3+2]-cycloaddition of benzynes with diazocarbonyl reagents. We postulate that this transformation involves the generation of (1H-indazol-1-yl)silver to activate a subsequent arylation with the second benzyne.
A direct coupling of 2H-indazoles' C3 position and acyl groups has been achieved to produce 3-acyl-2H-indazoles. The Ni(ii)-catalyzed acylation might proceed through a radical pathway for the reaction of 2H-indazoles with either aryl or alkyl aldehydes in the presence of the free radical initiator TBHP and additive PivOH. This method provided a superior approach to fulfil the direct C3-acylation of
visible-light-induced self-catalyzed energy transfer was developed. This method utilized a self-catalyzed energy transfer process between 2H-indazoles and α-ketoacids, offering advantages like absence of photosensitizers, metal catalysts, and strong oxidants, broad substrate compatibility, and operational simplicity under mild conditions.