Pyrazolopyridines. Part 5. Preparation and reactions of pyrazolo[3,4-c]pyridines

Abstract

A series of pyrazolo[3,4-c]pyridines has been prepared by nitrosation of 3-acetamido-4-methylpyridines and subsequent rearrangement and cyclisation of the N-acetyl-N-nitroso-compounds produced. The reactions of the pyrazolo[3,4-c]pyridines have been investigated. 1- and 2-Acetyl and 1- and 2-benzyl compounds were obtained and their structures elucidated spectroscopically. The ring system readily undergoes electrophilic substitution in the 3-position. 7-Chloropyrazolo[3,4-c]pyridine has been shown to be more susceptible to nucleophilic substitution than the isomeric 5-chloro-compound.