title: Construction of pyrazolo[3,4-b]pyridines and pyrazolo[4,3-c]pyridines by ring closure of 3-acylpyridine N-oxide tosylhydrazones.
abstract: 3-Acylpyridine N-oxide tosylhydrazones give good overall yields of a mixture of pyrazolo[3,4-b]pyridines and pyrazolo[4,3-c]pyridines when treated with an electrophilic additive and an amine base. (Z)-Hydrazones cyclize readily, while (E)-hydrazones fail to react under the reported conditions. The reaction takes place at room temperature, and moderate regiocontrol over the cyclization can be achieved by varying the electrophile/solvent combination.
authors.affiliation: Department of Chemistry, Physics, and Geology, Winthrop University, Sims Science Building, Rock Hill, SC 29733 USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Lominac
authors.forename: Megan L
authors.initials: ML
authors.lastname: D'Angelo
authors.forename: Mark D
authors.initials: MD
authors.lastname: Smith
authors.forename: Darius A
authors.initials: DA
authors.lastname: Ollison
authors.forename: James M
authors.initials: JM
authors.lastname: Hanna