Synthesis and structural characterization of derivatives of 2- and 3-benzo[b]furan carboxylic acids with potential cytotoxic activity.

Derivatives of 2- and 3-benzo[b]furancarboxylic acids were prepared and evaluated for their cytotoxic potential in the National Cancer Institute, Bethesda, USA. Six compounds: 7-acetyl-6-hydroxy-3-methyl-2-benzofurancarboxylic acid (2), 6-hydroxy-7-(p-methoxycinnamoyl)-3-methyl-2-benzofurancarboxylic acid (4), 5-bromo-7-hydroxy-6-methoxy-2-benzofurancarboxylic acid methyl ester (6a), 6-acetyl-5-(O-ethyl-2'-diethylamino)-2-methyl-3-benzofurancarboxylic acid methyl ester (1f), 6-(O-ethyl-2'-diethylamino)-7-p-methoxycinnamoyl)-3-methyl-2-benzofurancarboxylic acid methyl ester hydrochloride (4b), 5-bromo-7-(O-ethyl-2'-diethylamino)-6-methoxy-2-benzofurancarboxylic acid methyl ester (6b) showed significant cytotoxic activities against human cancer cell lines. In addition the crystal structures of 7-methoxy-2-benzofurancarboxylic acid methyl ester (7a) has been solved by X-ray structure analysis of single crystals.