title: Charting the Chemical Reactivity Space of 2,3-Substituted Furo[2,3-b]pyridines Synthesized via the Heterocyclization of Pyridine-N-oxide Derivatives.
abstract: A concise strategy for the synthesis of 2,3-substituted furo[2,3-b]pyridines is described. Mild, metal-free conditions were successfully applied to produce a range of 2-(alkyl or aryl)-3-ethylcarboxylate-furo[2,3-b]pyridines in yields of 50-91%. Then, the chemical reactivity of this heterocyclic framework was explored to develop straightforward methods for its functionalization. The pyridine moiety reactivity was successfully explored by C-H amination and borylation reactions, although C-H fluorination and radical C-H arylation processes were not as efficient. In addition, while the furopyridine core proved stable under basic conditions, the ring-opening reaction of the furan moiety with hydrazine generated a valuable new pyridine-dihydropyrazolone scaffold.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo , 14040-903 Ribeirão Preto-SP, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Fumagalli
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo , 14040-903 Ribeirão Preto-SP, Brazil.
authors.forename: Flavio
authors.initials: F
authors.lastname: da Silva Emery