2-Thiophenecarboxylic acid, tetrahydro-3-oxo-, methyl ester → 1,2-Dihydro-9-hydroxy-7-(3-methyl-2-octyl)-4-oxo-4H-thieno[2,3-c][1]benzopyran

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Reaction Steps

A solution of 2.5 g. (0.011 mole) of 5-(3-methyl-2-octyl)resorcinol and 2.0 g. (0.013 mole) of the methyl 3-oxo-2,3,4,5-tetrahydrothiophene-2-carboxylate in 50 ml. of absolute ethanol in a three-necked flask equipped with drying tube was cooled in an ice-waer bath and saturated with dry hydrogen chloride. The 5-(3-methyl-2-octyl)resorcinol was prepared according to the method of Adams, MacKenzie and Loewe (J. Am. Chem. Soc. 70, 664-8 (1948). The reaction mixture was allowed to stand for three days at room temperature, during which time a heavy yellow solid formed. The hydrogen chloride was evaporated, the mixture was concentrated and the solid was filtered and washed with ethanol. The yield of the crude benzopyrone thus obtained was 2.6 g. (59%), m.p. 190-205°.

Provenance & Evidence