Studies on the syntheses of heterocycles from 3-arylsydnone-4-carbohydroximic acid chlorides with N-arylmaleimides, [1,4]naphthoquinone and aromatic amines

3-Arylsydnone-4-carbohydroximic acid chlorides () could react with N-arylmaleimides () or 2-methyl-N-phenylmale-imide () to give 3-(3-arylsydnon-4-yl)-5-aryl-3a,6a-dihydro-pyrrolo[3,4-d]isoxazole-4,6-diones () or 6a-methyl-3-(3-arylsydnon-4-yl)-5-phenyl-3a,6a-dihydro-pyrrolo[3,4-d]isoxazole-4,6-diones (), respectively. However, 3-(arylsydnon-4-yl)-naphtho[2,3-d]isoxazole-4,9-diones () were obtained in good yield by the reaction of carbohydroximic acid chlorides with [1,4]naphthoquinone. Furthermore, 2-(3-arylsydnon-4-yl)benzoxazoles () and 2-(3-arylsydnon-4-yl)benzothiazoles () were obtained via the reaction of carbohydroximic acid chlorides with ortho-substituted aromatic amines .