Condensations of 4,4′-dichlorobenzophenone with diethyl succinate and dimethyl methylsuccinate give 3-alkoxycarbonylbut-3-enoic acids, which have been converted into 1-(p-chlorophenyl)naphthalene-2-carboxylic acids, 3-(p-chlorophenyl)-1-oxoindene-2-acetic acids and benzo[c]fluorenones. A pyridazinone derivative has also been obtained.