Pyridine → (2-Cyano-2-{[3,5-dichloro-4-(5-isopropyl-1-methyl-6-oxo-1,6-dihydro-pyridazin-3-ylmethyl)-phenyl]-hydrazono}-acetyl)-carbamic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 6-(4-amino-2,6-dichloro-benzyl)-4-isopropyl-2-methyl-2H-pyridazin-3-one (94) (148 mg, 0.45 mmol) in water (6 mL) and concentrated hydrochloric acid (3 mL) cooled to 0° C. was treated with a solution of sodium nitrite (37.3 mg, 0.54 mmol) in water (0.5 mL) via Pasteur pipette under the surface of the reaction mixture. This was followed by a water rinse (0.5 mL) of the Pasteur pipette. The resulting pale yellow solution was stirred at 0° C. for 45 min. At this time, the reaction was filtered through a pad of cotton and was drained directly into a solution of cyanoacetylurethane (77.3 mg, 0.49 mmol), pyridine (3 mL) and water (9 mL) cooled to 0° C. Upon mixing, orange-red solids immediately formed. This mixture was stirred at 0° C. for 30 min. At this time, the solids were collected by filtration through filter paper. The solids were washed with water and petroleum ether, air-dried under house vacuum, and then dried under vacuum to afford (2-cyano-2-{[3,5-dichloro-4-(5-isopropyl-1-methyl-6-oxo-1,6-dihydro-pyridazin-3-ylmethyl)-phenyl]-hydrazono}-acetyl)-carbamic acid ethyl ester (95) (192 mg, 86%) as an orange solid; ES-HRMS m/e calcd for C21H22Cl2N6O4 (M+H)+ 493.1153, found 493.1155. Exact Mass=492.1080; Molecular weight=493.3533.

Provenance & Evidence