Sulfuric Acid → 6-Methoxy-3-pentyl-2-benzofurancarboxylic acid ethyl ester

Participants

Reaction Steps

A mixture of 2-chloro-3-oxooctanoic acid (51.5 g) and sodium 3-methoxyphenolate (35 g) was refluxed with stirring in benzene (250 mL) for 7 hours, then stirred at room temperature overnight. The cooled reaction was washed with water (2×250 mL) and the dried (MgSO4) organic layer was evaporated to give 70 g of a brown oil. The crude product was purified by HPLC (diethyl ether-hexane; 1:19) to give 30.45 g of 3-oxo-2-(3-methoxyphenoxy)octanoic acid ethyl ester as a colorless oil. 3-Oxo-2-(3-methoxyphenoxy)octanoic acid ethyl ester (21.5 g) was added over 1 hour with stirring to sulfuric acid (22 mL) at -10° C. After 1 hour at -10° C., the reaction was diluted carefully with ice (400 g) and then extracted with diethyl ether (2×400 mL). The organic extracts were washed in turn with saturated sodium bicarbonate solution and with brine, then were combined, dried (MgSO4) and evaporated. The crude reaction product was crystallized from hexane to give 10.86 g of 6-methoxy-3-pentyl-2-benzofuranecarboxylic acid ethyl ester, mp 38°-41° C.

Provenance & Evidence