pathway for the Pd-catalyzed regiospecific ortho-acylation of azoarenes using benzylic ethers as acyl equivalents has been achieved. In the absence of palladium catalyst, amide compounds were formed by the reaction of azoarenes with benzylic ethers under certain conditions. Various mono-acylazobenzene and amide compounds were obtained in good yields (35 examples). The mono-acylated products and amide
Highly regioselective organo photocatalysis of 4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene) for the arylation of 2H-indazole is demonstrated.
The Mills reaction and cyclization of readily available 2‐aminobenzyl alcohols and nitrosobenzenes using thionyl bromide provided 2H‐indazoles in up to 88 % yields. In the metal‐free process, acetic acid played a crucial role for the both Mills reaction and cyclization. A brominated 2H‐indazole could also be obtained through the one‐pot sequence.
作者:Stephan A. Ohnmacht、Andrew J. Culshaw、Michael F. Greaney
DOI:10.1021/ol902537d
日期:2010.1.15
The efficient palladium-catalyzed synthesis of a range of substituted 2H-Indazoles via C−H arylation is reported. Reactions are performed on water and provide a direct and mild route toward 2,3-diaryl indazoles of widespread biological significance.
A straightforward and efficient method for the preparation of 2-aryl-2H-indazoles from ortho-alkyl substituted azoxybenzenes is presented. The reaction proceeds through base-catalyzed benzyl C–H deprotonation and cyclization to afford 2-aryl-2H-indazoles in good yields. This synthetic strategy can be applied to the construction of several fluorescent and bioactive molecules.