Abstract
The acylation of 4, 7-dihydroxycoumarin by the use of butyryl, decanoyl and dodecanoyl chlorides in pyridine gave products different from the case of the use of acetyl chloride, the products being 4-hydroxy-7-acyloxy-coumarin (C-type) and 3-acyl-4-hydr-oxy-7-acyloxycoumarin (A-type). The objective compounds possessing acyl in the 3-position alone, i. e. 3-acyl-4, 7-dihydroxycoumarin (B-type), were obtained only after saponif ication of the A-type products. Consideration of the present and the previous reactions using acetyl chloride seems to point that under such conditions, the acylation of 4, 7-dihydroxycoumarin takes place first in the phenol is hydroxyl at 7-, followed by attack on the 3-position, the enolic hydroxyl at 4-position remaining indifferent to acylation.
