Catalytically reductive ring closure for 1-acylamino-3,4-phthaloylacridones
AssigneeCiba-Geigy Corporation
InventorMaurice Grelat
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Abstract
The present invention relates to an advantageous novel process for producing 1-acylamino-3,4-phthaloylacridones by a hydrogenating ring-closure reaction of 1-acylamino-4-anilidoanthraquinone-2'-carboxylic acid esters. The ring-closure reaction according to the invention to the acridone ring is performed under mild conditions, with regard to temperature and alkalinity of the reaction medium, with the use of a hydrogenating catalyst. The first step to effect the ester formation can be carried out, as a single-vessel reaction, with the use of a polar solvent as the reaction medium, and of an alkylphosphoric acid dialkyl ester as the esterifying agent.
Claims11
A process for producing 1-acylamino-3,4-phthaloylacridones by reaction of 1-acylamino-4-bromoanthraquinone with anthranilic acid to 1-acylamino-4-anilidoanthraquinone-2'-carboxylic acid, esterification of the acid and subsequent reductive ring-closure reaction, which process comprises effecting esterification by means of an alkylphosphoric acid dialkyl ester, the alkyl groups each having 1 to 4 C atoms, and performing the reductive ring-closure reaction of 1-acylamino-4-anilido-2'-carboxylic acid ester of the formula ##STR4## to 1-acylamino-3,4-phthaloylacridone of the formula ##STR5## wherein R is phenyl, alkylphenyl or C.sub.1 -C.sub.8 -alkyl, R' is C.sub.1 -C.sub.4 -alkyl, and X is hydrogen, halogen or C.sub.1 -C.sub.4 -alkyl, by means of a hydrogenation catalyst and hydrogen in a basic reaction medium, said hydrogen being provided in amount just sufficient to accomplish ring closure.
Dependencies are inferred from the claim text.