Synthesis of substituted 1-[2-(adamantan-1-yl)ethyl]piperidines

Quaternary 1-[2-(adamantan-1-yl)ethyl]pyridinium bromides were reduced with sodium tetrahydridoborate in ethanol, and hydroarylation of the resulting 1-[2-(adamantan-1-yl)ethyl]-1,2,3,6-tetrahydropyridines with benzene in trifluoromethanesulfonic acid afforded phenylpiperidines with preferentially equatorial orientation of the phenyl substituent.     

Reduction of 4-arylazoindoles

It was established that 4-acetamido-5-hydroxyindole derivatives are formed in the reduction of 4-phenylazo-5-hydroxyindole derivatives with zinc dust in acetic acid in the presence of acetic anhydride and sodium acetate. However, p-semidine rearrangement of the intermediate hydrazo derivatives is observed in the analogous reduction of 4-arylazo-5-methoxyindoles, and 4-acetamido-5-methoxy-7-arylaminoindoles are formed. The latter are oxidized by oxygen and nitric acid to 4-oxo-7-arylimino-4,7-dihydroindoles; nitration of the arylimino ring occurs in some cases under the influence of nitric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1374–1379, October, 1980.     

Some transformations of 2,3-diaminoindole derivatives. Synthesis of indolo[2,3-b]quinoxalines

1-Methyl-3-methoxy- and 1-methyl-3-piperidino-3-acetamidooxindole anils, respectively, were obtained by oxidation of 1-methyl-2-arylamino-3-acetamidoindoles with oxygen in the presence of copper acetate in methanol and in a mixture of dimethylformamide and piperidine. When the oxindole anils are heated, they undergo cyclization to indolo[2,3-b]quinoxalines. Indolo[2,3-b]quinoxaline N-oxides were obtained from the latter by the usual method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1645–1647, December, 1977.     

Rearrangement of the semidine type in the indole series. Synthesis of 2-arylamino-3-acetamidoindoles

A previously unknown (in the indole series) rearrangement of the semidine type leading leading to the formation of 1-methyl-2-arylamino-3-acetamidoindoles, the oxidation of which gives 1-methylisatin -anils, occurs when 1-methyl-3-arylazoindoles are treated with zinc in acetic acid in the presence of acetic anhydride and sodium acetate. Data from the UV, IR, and PMR spectra are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 353–356, March, 1977.