An efficient access to 3,6-disubstituted 1H-pyrazolo[3,4-b]pyridines via a one-pot double SNAr reaction and pyrazole formation
作者:Yong-Li Zhong、Matthew G. Lindale、Nobuyoshi Yasuda
DOI:10.1016/j.tetlet.2009.02.142
日期:2009.5
A general and efficient synthetic method for the synthesis of biologically important series of 3,6-disubstituted-1H-pyrazolo[3,4-b]pyridines was discovered. 2,6-Difluoropyridine was deprotonated using 1.1 equiv of n-BuLi in THF at <-60 degrees C, followed by quenching with a variety of Weinreb amides to generate 2,6-Difluoro-3-ketopyridines in high yields. A mild tandem reaction sequence of selective nucleophilic Substitution of the 6-fluoride with a variety of nucleophiles, followed by hydrazine substitution of the 2-fluoride and pyrazole formation in a one-pot fashion afforded a series of 3,6-disubstituted-1H-pyrazolo[3,4-b]pyridines in moderate to good yields. (C) 2009 Elsevier Ltd. All rights reserved.