A New Synthetic Approach to Pyrazolo[3,4-c]-1,2,5-oxadiazoles
作者:Pier Giovanni Baraldi、Maria J. Pineda de las Infantas、Stefano Manfredini、Romeo Romagnoli
DOI:10.1055/s-2000-6231
日期:——
4-aryl-substituted-6-methyl-4H-pyrazolo[3,4-c]-1,2,5-oxadiazoles 15-21 were easily obtained through the oxidation reaction mediated by lead(IV) acetate of 5-methyl-4-nitroso-2-phenyl-2H-pyrazol-3-ylamines 8-14 in 88-97% yields.
An efficient synthetic approach to synthesize N-aryl-5-aminopyrazoles from anilines via a one-pot, telescoped reaction performed in entirely aqueous conditions has been developed. This protocol provides a rapid, convenient method to prepare N-aryl-5-aminopyrazoles, useful building blocks for the synthesis of several bicyclic nitrogen heterocycles, by avoiding the isolation of the toxic intermediate arylhydrazines and the use of a metallic reductant.