Phosphorus oxychloride → 4-Chloro-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 4-hydroxy-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylic acid (35.4 g, 192 mmol), catalytic amount of DMF (3 drop), and POCl3 (178 mL, 1.92 mol) was heated for 2 days at 90° C., and then the POCl3 was removed under reduced pressure. The crude material was quenched with ice, and the reaction mixture was stirred for 2 hours at room temperature. The precipitates formed out of the solution was filtered off and washed with ether. The precipitates collected were triturated with ether to afford 11.7 g (30%) of the desired product. The filtrate was extracted with EtOAc (2×). The combined organic layers were dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude product that was triturated with ether and dried under reduced pressure to afford additional 9.56 g (24%) of the desired product. A total of 21.29 g (55%) of the desired product was obtained.

Provenance & Evidence