Phosphorus oxychloride → 4-Chloro-1,2,5-trimethyl-6-oxo-1,6-dihydropyridine-3-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

Phosphorous oxychloride (20.0 mL, 216 mmol) was added to 4-hydroxy-1,2,5-trimethyl-6-oxo-1,6-dihydropyridine-3-carboxylic acid ethyl ester and heated to 80° C. After two hours, the reaction mixture was concentrated under reduced pressure. The resulting residue was poured onto ice and, carefully neutralized with saturated NaHCO3, and diluted with EtOAc. After stirring for 16 hours, the organic layer was separated and the aqueous layer was reextracted with EtOAc repeatedly. The pH of the aqueous layer was adjusted to pH 11 with saturated K2CO3 and extracted with EtOAc (2×). The combined organic extracts were dried (MgSO4) and concentrated under reduced pressure to give 3.42 g (89%) clean desired product.

Provenance & Evidence