Hydrochloric Acid → HCID 21270174, compound

Participants

Reaction Steps

6,7-Dihydroxy-3-(4-aminophenyl)-4H-1-benzopyran-4-one [see Example 51a] (538 mg) is dissolved in a mixture of dimethylformamide and water 15:85 (5 ml) and the solution is heated to 90° in the presence of benzenesulfonyl chloride (210 mg). After 15 minutes the pH has dropped to 3 and it is adjusted to 9 by addition of a 25% sodium hydroxide solution. Benzenesulfonyl chloride (additional 143 mg) and 25% sodium hydroxide solution (total amount used: 1 ml) are added in the same way until the pH does not vary any more. Aqueous hydrochloric acid is then added to lower the pH to 3 and the solution is cooled until precipitation occurs. The precipitate is filtered, washed with water and dried to give 6,7-dihydroxy-3-(4-phenylsulfonylaminophenyl)-4H-1-benzopyran-4-one, m.p. 285°-286°.

Provenance & Evidence