Hydrochloric Acid → Ethyl 6-difluoromethoxy-3-ethyl-4-oxo-3,4-dihydrobenzo[4,5]furo[2,3-d]pyridazine-9-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of ethyl 6-difluoromethoxy-4-oxo-3,4-dihydrobenzo[4,5]furo[2,3-d]pyridazine-9-carboxylate (from step 6 of example 4) (261 mg, 0.803 mmol) in n,n-dimethyl formamide, sodium hydride (33 mg, 0.803 mmol) was added at 20-30° C. under nitrogen. Ethyl bromide (95.4 mg, 0.88 mmol) was added to the reaction mixture. Progress of reaction was monitored by TLC. At the end, reaction mixture was cooled to 0-10° C. Water (100 ml) was added dropwise to the reaction mixture at 0-10° C. and acidified with dilute hydrochloric acid. The precipitate obtained was filtered and dried in oven. It was purified by silica gel column chromatography using 10% ethyl acetate in chloroform. White colored solid (130 mg) was obtained.

Provenance & Evidence