Copper−Diamine-Catalyzed <i>N</i>-Arylation of Pyrroles, Pyrazoles, Indazoles, Imidazoles, and Triazoles
作者:Jon C. Antilla、Jeremy M. Baskin、Timothy E. Barder、Stephen L. Buchwald
DOI:10.1021/jo049658b
日期:2004.8.1
This paper details the copper-catalyzed N-arylation of π-excessive nitrogenheterocycles. The coupling of either aryl iodides or aryl bromides with common nitrogenheterocycles (pyrroles, pyrazoles, indazoles, imidazoles, and triazoles) was successfully performed in good yield with catalysts derived from diamine ligands and CuI. General conditions were found that tolerate functional groups such as
maleimides with 2-arylindazoles via C-H activation have been demonstrated. The reaction affords 3-(2-(2H-indazol-2-yl)phenyl)succinimide and 3-(2-(2H-indazol-2-yl)phenyl)maleimide derivatives in high yields with wide functional group tolerance. A mechanistic study was performed to depict C-H bond cleavage that might be involved in the turnover limiting step.
A simple and direct approach for the regioselective construction of the privileged 2H‐indazole scaffold is described. The developed one‐pot strategy involves phospholene‐mediated N−N bond formation to access 2H‐indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2‐nitrobenzaldehydes and primary
A general and practical regioselective approach for the C–H amination of 2H-indazoles under transition-metal-free conditions was developed. A series of substrates were tested showing eminent functional group tolerance and affording the C–N functionalization products in good to excellent yields. Mechanism studies revealed that a radical process was involved in this transformation.
Visible-light-mediated direct C3-arylation of 2<i>H</i>-indazoles enabled by an electron-donor–acceptor complex
作者:Kim Christopher C. Aganda、Junyoung Kim、Anna Lee
DOI:10.1039/c9ob02074h
日期:——
A mild visible-light-mediated, photocatalyst-free arylation of 2H-indazoles was developed. The formation of an electron donor–acceptor complex by 2H-indazoles and aryl diazonium salts in the presence of pyridine allows the direct arylation of 2H-indazoles under visible-light irradiation. This process provides an efficient route for the synthesis of C3-arylated-2H-indazoles, which are important scaffolds