2,3-dihydro-7-hydroxy-8-pentyl-4H-1-benzopyran-4-one → 2-[5-[(3,4-dihydro-4-oxo-8-pentyl-2H-1-benzopyran-7-yl)oxy]pentyloxy]benzenepropanoic acid methyl ester

Participants

Reaction Steps

Using the procedure of example 11 and starting with 1.25 g (5.34 mmol) of 2,3-dihydro-7-hydroxy-8-pentyl-4H-1-benzopyran-4-one (from example 117) and 1.64 g (4.76 mmol) of 2-[[5-[(methylsulfonyl)oxy]pentyl]oxy]benzenepropanoic acid methyl ester (from example 72), 2-[5-[(3,4-dihydro-4-oxo-8-pentyl-2H-1-benzopyran-7-yl)oxy]pentyloxy]benzenepropanoic acid methyl ester was obtained in 98% yield (2.52 g) as a pale-yellow oil. This diester (5.18 mmol) was saponified with 7.8 mL of 3N aqueous lithium hydroxide in 25 mL of tetrahydrofuran, at room temperature, for 48 hr. Work-up as in example 4 gave 2-[5-[(3,4-dihydro-4-oxo-8-pentyl-2H-1-benzopyran-7-yl)oxy]pentyloxy]benzenepropanoic acid as an oil. This material was flash chromatographed on silica gel eluting with ethyl acetate-hexane mixtures giving 0.69 g (28.5%) of pure acid as a solid. Recrystallization from acetonitrile gave a colorless solid, mp 86°-87° C.

Provenance & Evidence