Pd-Cu–Mediated Synthesis of 2-Substituted Imidazo[1,2-α]pyridines in Water

Abstract

The reaction of 2-amino-1-(2-propynyl)pyridinium bromide with various iodobenzenes, catalyzed by Pd-Cu, in the presence of sodium lauryl sulfate as the surfactant and cesium carbonate as the base, in water, leads to the formation of 2-substituted imidazo[1,2-α]pyridines.

Keywords:

• Aryl iodide
• imidazopyridine
• Pd-catalyzed
• sodium lauryl sulfate
• Sonogashira coupling

ACKNOWLEDGMENTS

The authors thank the Research Council of Shahrood University of Technology for the support of this work.

Notes

^a Reaction conditions: 1 (1 mmol), 2a–h (1 mmol), Cs₂CO₃ (3 mmol), Pd(PPh)₃Cl₂ (3 mol%), CuI (7 mol%), Sodium laurylsulfate (7 mol%), and degassed water (5 mL) at 60 °C for 10 h.

^a Reaction conditions: 1 (1 mmol), 2a (1 mmol), base (3 mmol), Pd(PPh)₃Cl₂ (3 mol%), CuI (7 mol%), sodium laurylsulfate (7 mol%), and degassed water (5 mL) at 60 °C for 10 h.

^b Isolated yields.

^a Reaction conditions: 1 (1 mmol), 2a (1 mmol), Cs₂CO₃ (3 mmol), and degassed water (5 mL) at 60 °C for 10 h.

^b Isolated yields.

^c Reaction time: 12 h.

^d Reaction time: 7 h.