Sodium hydride → Benzyl 4-(3,3-dimethoxypropyl)-6-methoxy-3-oxo-3,4-dihydroquinoxalin-1(2H)-carboxylate

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Reaction Steps

To a solution of benzyl 6-methoxy-3-oxo-3,4-dihydroquinoxalin-1(2H)-carboxylate (291 mg, 0.932 mmol) in N,N-dimethylformamide (5 ml), lithium bromide (89 mg, 1.025 mmol) and subsequently sodium hydride (55%, 45 mg, 1.025 mmol) were added under a nitrogen gas atmosphere in an ice bath. The solution was stirred at room temperature for 1 hour. The reaction solution was cooled on ice again and 3-bromopropionaldehyde dimethyl acetal (0.184 ml, 1.212 mmol) was added thereto. After stirring overnight at room temperature, the reaction solution was diluted with ethyl acetate and washed sequentially with a saturated sodium hydrogen carbonate aqueous solution and saturated sodium chloride solution. After drying the resultant over anhydrous sodium sulfate, the solvent was removed under reduced pressure and the obtained residue was purified by silica gel column chromatography (n-hexane/ethyl acetate) to yield 386 mg (quantitative) of the title compound in the form of a yellowish brown oil.

Provenance & Evidence