2,3-dihydro-7-hydroxy-8-propyl-4H-1-benzopyran-4-one → 5-(4-methoxy-4-oxobutoxy)-2-[6-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]hexyl]benzenepropanoic acid methyl ester

Participants

Reaction Steps

Using the procedure of example 11 and starting with 0.28 g (1.4 mmol) of 2,3-dihydro-7-hydroxy-8-propyl-4H-1-benzopyran-4-one and 0.64 g (1.4 mmol) of 2-[6-[(methylsulfonyl)oxy]hexyl]-5-(4-methoxy-4-oxobutoxy)benzenepropanoic acid methyl ester (from example 53), 5-(4-methoxy-4-oxobutoxy)-2-[6-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]hexyl]benzenepropanoic acid methyl ester was obtained in 86.7% yield (0.69 g) as an oil. This diester (1.21 mmol) was saponified with 2 mL of 3N aqueous lithium hydroxide in 20 mL of tetrahydrofuran, at room temperature, for 24 hr. Work-up as in example 4 gave a light-brown oily acid which was flash-chromatographed on silica gel, eluting with 95:5:1 chloroform-methanol-acetic acid. There was obtained 0.6 g (91.8%) of pure 5-(3-carboxypropoxy)-2-[6-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]hexyl]benzenepropanoic acid. Recrystallization from hexane-ethyl acetate gave 0.49 g (75%) of a colorless solid, mp 119°-120° C.

Provenance & Evidence