First Synthesis of 5-Chloro-7-[1,3]oxazolo[4,5-b]pyridin-2-ylquinolin-8-ol by Pd-Catalyzed Arylation

Abstract

5-Chloro-7-[1,3]oxazolo[4,5-b]pyridin-2-ylquinolin-8-ol was synthesized by a Pd-catalyzed arylation, which proceeds efficiently with 2 equivalents of benzylated clioquinol and 1 equivalent of oxazolo[4,5-b]pyridine. The product was smoothly debenzylated by boron trichloride in dichloromethane.

Keywords:

• Arylation
• clioquinol
• oxazolopyridine
• palladium
• synthesis

ACKNOWLEDGMENTS

We thank the European Union for a Marie Curie fellowship (MIF1-CT-2005-514549), PERCH-CIC, Faculty of Science, Mahasarakham University, for the research fellowship, and Leeds University for support.

Notes

^a Conditions: 2 (2 mol equiv), 3 (1 mol equiv), 5 mol% Pd, 20 mol% ligand, and Cs₂CO₃ (2 mol equiv).

^b Isolated yield.

^c Reaction run at room temperature; no product was detected.

^d 10 mol% Pd, 40 mol% PPh₃.

^e 10 mol% Pd, 20 mol% PPh₃.