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Paper | Regular issue | Vol 27, No. 3, 1988, pp.733-743
Published online, 1st January, 1970
DOI: 10.3987/COM-87-4408
Preparation of Pyrazolo[1,5-a]pyridine and [1,2,4]Triazolo[1,5-a]pyridine Derivatives from 1,6-Diaminopyridine-2-thiones

Pedro Molina,* Alberto Tárraga, and Concepción Garcia

*Departmento de Química Orgánica, Facultad de Ciencias, Universidad de Murcia, 30071 Murcia, Spain

Abstract

The 1,6-diaminopyridine-2-thiones (1a and 1b)react with α-halocarbonyl compounds to give the pyrido [2,1-b][1,3,4]thiadiaziniumsalts (2) which undergo base-catalyzed ring-contraction to give the pyrazolo[1,5-a]pyridines (3) or (4). The reactions of the N-aminoheterocycles (1a and 1b) with nitriles lead directly to [1,2,4] triazolo-[1,5-a]pyridines (5).