Ring transformations involving chloroheterocycles. Part I. Reaction of chloronaphthyridines with hydrazine hydrate
Abstract
4-Chloro-1,8-naphthyridines and 4-chloro-6,8-dimethyl-1,7-naphthyridine rearrange on treatment with hydrazine hydrate in a sealed tube at 150 °C to give pyrazol-5-ylpyridines. The products undergo cyclisation with triethyl orthoesters and with cyclohexanone to form new ring systems, pyrazolo[1,5-c]pyrido-[3,2-e]- and -[4,3-e]-pyrimidines.