Microwave-assisted synthesis of 1-aryl-1H-indazoles via one-pot two-step Cu-catalyzed intramolecular N-arylation of arylhydrazones
摘要:
A highly efficient one-pot two-step microwave procedure was developed for the synthesis of 1-aryl-1H-indazoles. Microwave heating of 2-halobenzaldehydes or 2-haloacetophenones with phenylhydrazines at 160 degrees C for 10 min quantitatively yielded the arylhydrazones, which were further cyclized to give 1-aryl-1H-indazoles via CuI/diamine-catalyzed N-arylation under microwave heating (160 degrees C, 10min). Good to excellent yields were observed for 2-iodo, 2-bromo, and 2-chloro benzaldehydes or acetophenones. (c) 2005 Elsevier Ltd. All rights reserved.
Facile palladium-catalysed synthesis of 1-aryl-1H-indazoles from 2-bromobenzaldehydes and arylhydrazines
作者:Chan Sik Cho、Dong Kwon Lim、Nam Ho Heo、Tae-Jeong Kim、Sang Chul Shim
DOI:10.1039/b312154m
日期:——
2-Bromobenzaldehydes react with arylhydrazines in toluene at 100 [degree]C in the presence of a catalytic amount of a palladium catalyst and phosphorus chelating ligands such as 1,1[prime or minute]-bis(diphenylphosphino)ferrocene and 1,3-bis(diphenylphosphino)propane along with NaO-t-Bu to afford 1-aryl-1H-indazoles in good yields.
A general synthesis of 1‐aryl‐1‐H‐indazoles from o‐halogenated aryl aldehydes or ketones and aryl hydrazines was described. This protocol included an intermolecular condensation and a ligand‐free copper‐catalyzedintramolecular Ullmann‐type coupling reaction. This method was applied to a wide range of substrates to produce the indazole products in good yields.
Copper Powder–Catalyzed C-N Bond Formation of Arylhydrazones of 2-Bromobenzaldehydes Leading to 1-Aryl-1<i>H</i>-indazoles
作者:Hye Kyung Lee、Chan Sik Cho
DOI:10.1080/00397911.2011.614714
日期:2013.2.1
Arylhydrazones of 2-bromobenzaldehydes and its analogs are cyclized in PEG-400 at 110 degrees C in the presence of a catalytic amount of copper powder along with NaOtBu to give 1-aryl-1H-indazole derivatives in good yields.