SYNTHESIS OF N-HYDROXYINDOLES

The basic synthetic methods for obtaining N-hydroxyindoles were studied. The first method is intramolecular reductive cyclization of ortho-substituted nitroaromatic compounds by various reducing agents. Nitrophenyl acetaldehydes (synthesis by Acheson), N,N-disubstituted amino-2-nitrostyrenes (synthesis by Somei), ortho-nitroketoetheres of different structure or 1-(o-nitroarene)-1-cyanoalkylnitroketones, ortho-nitrophenylacetonitriles were used as substrates for the synthesis of N-hydroxyindoles. Titanium chloride (III), zinc in THF solution of ammonium chloride or in acetic acid, stannous chloride in ethanolic HCl, and hydrogen with application of catalytic agent on basis of noble metals (platinum, palladium) were used as reduction agents. The second method is a [3+2]-cycloaddition with nitrozoaromatic compounds to alkynes or deoxygenation ortho-nitro substituted aromatic compounds with subsequent intramolecular cyclization. The third method is catalytic oxidation of 2,3-dihydroindoles or different indoles by concentrated hydrogen peroxide with application of of tungstate sodium as catalyst. We attended special attention to synthesis of functional derivatives of N-hydroxyindole-5,6-dicarboxylic acids because these compounds were synthesized from commercially available basic materials using well known synthetic methods and without using expensive catalysts. Indoles of various designs were synthesized. They may be building blocks for the synthesis of biologically active substances, phthalocyanines of different structures having mesomorphic and catalytic properties. Compounds of this class of heterocycles were found among many natural products and they can be used as therapeutic agents, for example, as inhibitors of human lactate dehydrogenase of isoforms 5, selective inhibitors of monoamine oxidase A and B, and N-methoxyindole can be used to treat breast cancer. For citation:Chirkova Zh.V. Synthesis of N-hydroxyindoles. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 4-20.