p-Toluenesulfonic acid → 5-Chloroimidazo[1,2-A]pyridine

Participants

Reaction Conditions

Reaction Steps

To a solution of pTSA (103 mg, 0.65 mmol) in water (5 ml) and ethanol (20 ml) was added chloroacetaldehyde dimethyl acetal (2.0 g, 16.0 mmol) at room temperature. The reaction was stirred at 65° C. for 30 minutes and then cooled to room temperature and a saturated solution of NaHCO3 was added dropwise until pH 7 was reached. 2-Amino-6-chloropyridine (2.1 g, 16 mmol) in 4:1 ethanol:water (20 ml) was then added and the reaction was heated at reflux for 3 hours. After cooling and concentrating at reduced pressure, the residue was purified by FCC (98:2 DCM/MeOH) to give the title compound (850 mg, 36%) as brown oil.

Provenance & Evidence