Charting the Chemical Reactivity Space of 2,3-Substituted Furo[2,3-b]pyridines Synthesized via the Heterocyclization of Pyridine-N-oxide Derivatives

• DOI: 10.1021/acs.joc.6b01329
• Publication Date: 2016-07-26T18:44:09Z
• Authors: Fernando Fumagalli; Flavio da Silva E...
• Keywords: Reactivity; Pyridine-N-oxide

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 2-(alkyl or aryl)-3-ethylcarboxylate-furo[2,3-b]pyridines in yields 50–91%. Then, chemical reactivity this heterocyclic framework was explored develop straightforward methods its functionalization. The pyridine moiety by C–H amination and borylation reactions, although fluorination radical arylation processes not as efficient. In addition, while furopyridine core proved stable under basic conditions, ring-opening reaction furan with hydrazine generated valuable new pyridine-dihydropyrazolone scaffold.