2-Aryl-4-azaindain-1,3-diones

2-Pheny1-4-azaindan-1,3-dione and 2-(p-dimethylaminophenyl)-4-azaindan-1,3-dione are synthesized by condensing 4-azaphthalide with benzaldehyde and p-dimethylaminobenzaldehyde. 4-Azaphthalide reacts with p-nitrobenzaldehyde in hot acetic anhydride to give 3-(p-nitrobenzylidene)-4-azaphthalide, rearranged by sodium methoxide to 2-(p-nitrophenyl)-4-azaindan-1,3-dione. 2-Phenyl-and 2-(p-nitrophenyl)-4-azaindandiones are also obtained by sodium methoxide rearrangement of the products of reaction of quinolinic anhydride with phenylacetic and p-nitrophenylacetic acids. 2-Aryl-4-azaindandiones are deeply colored substances only slightly soluble, and without sharp melting points. They undergo methylation at the nitrogen atom, to give N-methylbetaines. The IR absorption spectra show that 2-ary]-4-azaindandiones exist in a strongly polarized enol form in the solid state.