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.
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.
Cobalt(III)-Catalyzed Synthesis of Indazoles and Furans by C–H Bond Functionalization/Addition/Cyclization Cascades
作者:Joshua R. Hummel、Jonathan A. Ellman
DOI:10.1021/ja5116452
日期:2015.1.14
reported heterocycle syntheses also demonstrate the use of directing groups that have not previously been applied to Co(III)-catalyzedC–H bond functionalizations. Additionally, the synthesis of furans demonstrates the first example of Co(III)-catalyzedfunctionalization of alkenyl C–H bonds.
Visible-Light-Promoted Metal-Free 3-Arylation of 2-Aryl-2H-indazoles with Triarylsulfonium Salts
作者:Kai Sun、Bing Yu、Anzai Shi、Panjie Xiang、Yanxuan Wu、Chang Ge、Yan Liu
DOI:10.1055/a-1938-9550
日期:2023.3
An efficient approach for the photosynthesis of various arylated 2-aryl-2H-indazoles (38 examples) in moderate to good yields (up to 87% yield) under mild conditions was developed by employing 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as an inexpensive photocatalyst. This protocol features wide substrate scope, good functional group tolerance, and operational simplicity. In addition