203. β-Aroylpropionic acids. Part IX. Their conversion into 1 : 2-benzanthraquinones

Abstract

The ester (I) is cyclised with 75% VIV sulphuric acid to 3 : 4-dihydro-3 : 7dimethylnaphthalene-1 : 2-dicarboxylic anhydride, which is then dehydrogenated to 3 : 7-dimethylnaphthalene-1 : 2-dicarboxylic anhydride. The latter with arylmagnesium halides gives a mixture of 1-and 2-aroyl-3: 7-dimethyl-2-and -1-naphthoic acid. These are separated and reduced to the corresponding benzylnaphthoic acids, which are cyclised and then oxidised to 1 : 2-benzanthraquinones.ETHYL ~-METHYL-~-$-TOLYLBUTYRATE was condensed with ethyl oxalate in presence of potassium ethoxide to give the ethoxalyl ester (I), which was cyclised and then dehydrogenated to 3 : 7-dimethylnaphthalene-1 : 2-dicarboxylic anhydride (111). Interaction of this anhydride with phenyl-or $-methoxyphenyl-magnesium halide gave a mixture of the aroyl-acids (IV and V; R = H or MeO) , the former predominating.