Potassium Carbonate → 4-Chloro-5-methoxy-2-methyl-2,3-dihydropyridazin-3-one

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Reaction Steps

10 g (55.8 mmoles) of intermediate 3a are placed in the presence of 115 g (837 mmoles) K2CO3 in 725 mL MeOH. The reaction medium is agitated for 1 h under reflux then filtered through celite. The filtrate is concentrated to dryness and the residue solubilized in CH2Cl2 and washed with water. After drying over Na2SO4, the organic phases are evaporated and the residue obtained is purified by silica gel flash chromatography (CH2Cl2—AcOEt, gradient 100:0 to 60:40 over 45 min). 9.14 g of intermediate 4b are thus obtained in the form of a white solid (yield 94%). TLC silica gel 60 F 254 Merck, CH2Cl2—AcOEt: 50:50, Rf=0.36.

Provenance & Evidence