94015-27-7Relevant articles and documents
Preparation of some Thiopyranopyridine Derivatives
Clarke, Kenneth,Goulding, John,Scrowston, Richard M.
, p. 1501 - 1505 (2007/10/02)
In the first systematic study of thiopyranopyridines in which the sulphur atom is separated from the pyridine ring by one carbon atom, the four isomeric enol esters, ethyl 5-hydroxy-8H-thiopyranopyridine-6-carboxylate (4b), ethyl 8-hydroxy-5H-thiopyranopyridine-7-carboxylate (5b), and ethyl 4-hydroxy-1H-thiopyrano- and pyridine-3-carboxylate (6b) and (7b), have been synthesised.Improved methods for the preparation of their pyridine precursors are described.With phenylhydrazine, the enol esters (4b) - (7b) give condensed pyrazole derivatives (15) - (18), which have dipolar structures; with hot mineral acid they undergo decarboxylative hydrolysis, to give the corresponding oxothiopyranopyridines (4a) - (7a).