1,3-Dibromopropane → 8-(3-bromopropoxycarbonyl)-3-methyl-4-oxo-2-phenyl-4H-1-benzopyran

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Reaction Steps

30 g of 1,3-dibromopropane was added dropwise at ambient temperature to a suspension of 30 g of sodium3-methyl-4-oxo-2-phenyl-4H-1-benzopyran-8-carboxylate in 150 ml of dimethylformamide and 35 ml of water. The reaction mixture was stirred at ambient temperature for 5 days. 100 ml of water was added and stirring was continued for a further 15 minutes. The precipitate was filtered off by suction, washed with water and purified by flash chromatography on silica gel, eluting with chloroform:ethyl acetate 95:5. The collected fractions were evaporated to dryness in vacuo and the residue was recrystallized from ethanol to give 27.7 g of the title compound, m.p. 114°-115° C.

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