反应详情

A mixture of ethyl 4-(2-methylphenyl)-2-oxo-2,6,7,8-tetrahydrocyclopenta[g][1]benzopyran-3-carboxylate (5.0 g), concentrated hydrochloric acid (13 ml) and acetic acid (25 ml) was refluxed for 12 hours. To this reaction mixture was added water, whereupon 4-(2-methylphenyl)-2-oxo-2,6,7,8-tetrahydrocyclopenta[g][1]benzopyran-3-carboxylic acid was obtained as crystals (4.5 g, 97.8%). Recrystallization from acetone-hexane gave colorless prisms, mp 213°-214° C.

1. temperaturewas refluxed for 12 hours