The cyclocondensation of aniline (VII) with ethyl 2-oxocyclo-hexanecarboxylate (VIII) by means of HCl in refluxing benzene gives 9-acridone (IX), which by treatment with refluxing POCl3 is converted to 9-chloroacridine (X). Finally, this compound is treated with anhydrous NH3 in p-cresol), or with ethanolic ammonia with a Cu catalyst.
This compound can be prepared by two different methods: 1) By cyclocondensation of p-anisidine (I) with 2-oxocyclohexanecarboxylate (II) to 7-methoxy-1,2,3,4-tetrahydroacridone (III), which by treatment with refluxing POCl3 is converted to 9-chloro-7-methoxy-1,2,3,4-tetrahydroacridine (IV). This compound is converted to final product by treatment with NH3 in refluxing p-cresol. 2) By cyclocondensation of 5-methoxyisatin (V) and cyclohexanone (VI) in concentrated aqueous ammonia at 150 C to 7-methoxy-1,2,3,4-tetrahydroacridine-9-carboxamide (VII), followed by a Hoffman degradation with potassium hypobromite.
By cyclocondensation of isatine (V) with cyclohexanone (II) and aqueous concentrated NH3 at 150 C in a pressure vessel to acridine-9-carboxamide (VI), followed by a Hoffman degradation with Br2 and sodium methoxide in methanol