Sodium Hydroxide → 2-[5-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]pentyl]benzenepropanoic acid

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Reaction Steps

Using the procedure of example 4, 2-[5-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]pentyl]benzenepropanoic acid methyl ester was prepared, in 67.5% yield, starting from 0.35 g (1.69 mmol) of 2,3-dihydro-7-hydroxy-8-propyl-4H-1-benzopyran-4-one and 0.54 g (1.5 mmol) of 2-(5-iodopentyl)benzenepropanoic acid methyl ester. A 0.5 g (1.14 mmol) sample of this ester was treated with 20 mL of methanol and 3 mL of aqueous 1N sodium hydroxide. The mixture was stirred and refluxed for 2.5 hr and then the solvent was removed in vacuo. The residue was diluted with water, acidified, and worked-up with ether in the usual manner. The product was recrystallized from hexane-ethyl acetate giving 2-[5-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]pentyl]benzenepropanoic acid as a colorless solid, mp 94°-96° C., in 58.2% overall yield.

Provenance & Evidence