Cu<sup>II</sup>–hydrotalcite catalyzed one-pot three component synthesis of 2H-indazoles by consecutive condensation, C–N and N–N bond formations
作者:Avvari N. Prasad、Rapelli Srinivas、Benjaram M. Reddy
DOI:10.1039/c2cy20590d
日期:——
An efficient and straightforward synthesis of 2H-indazoles is achieved from 2-bromobenzaldehydes, primary amines and sodium azide through consecutive condensation, CâN and NâN bond formations, catalyzed by a novel heterogeneous CuIIâHT catalyst. The recoverable heterogeneous CuIIâHT catalyst exhibited an impressive activity for the title reaction without any additives (expensive ligands, etc.). Heterocyclization proceeds through CâN and NâN bond formation, which is the key step to deliver the desired 2H-indazole scaffold. A series of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily accessible starting materials by employing this protocol.
Preparation of Polyfunctional Indazoles and Heteroarylazo Compounds Using Highly Functionalized Zinc Reagents
作者:Benjamin Haag、Zhihua Peng、Paul Knochel
DOI:10.1021/ol901585k
日期:2009.10.1
available 2-chloromethylarylzinc reagents react with functionalized aryldiazoniumtetrafluoroborates providing polyfunctional indazoles. Selective metalations of these 2-aryl-2H-indazoles afford new polycyclic aromatics. The performance of a chemoselective addition of diheteroarylzincs to aryldiazonium salts allows an efficient preparation of new heterocyclic azo compounds.