Hydrochloric Acid → 2,3-Dichloro-5-(pyrrolidin-1-ylcarbonyl)pyridine

Participants

Reaction Steps

Oxalyl chloride (3.2 mL; 36.0 mmol) was added to a solution of 5,6 dichloronicotinic acid (5.76 g; 30.0 mmol) and 4M hydrogen chloride in dioxan (7.5 mL; 30.0 mmol) in DCM (50 mL). The mixture was stirred at RT for 18 hours, the DCM evaporated in vacuo, the residue azeotroped with toluene (2×15 mL) then added to a solution of pyrrolidine (3.0 mL; 36.0 mmol) and triethylamine (10.0 mL; 72 mmol) in DCM (150 mL). The mixture was stirred at RT for 6 hours, the DCM evaporated in vacuo, the residue partitioned between water (75 mL) and ethyl acetate (100 mL), the organic layer washed with brine, dried (MgSO4) and evaporated in vacuo. The residue was chromatographed on silica, eluting with 50% ethyl acetate in isohexane, to give the desired compound which was further purified by crystallisation from ethyl acetate and isohexane (6.88 g). 1H NMR δ (CDCl3): 1.9 (m, 4H), 3.4 (m, 2H), 3.6 (s, 3H), 7.9 (s, 1H) and 8.4 (s, 1H); m/z 245 (M+H)+.

Provenance & Evidence