The synthesis of 2,3,4,6-tetrahydro-5-hydroxy-2,6-dimethyl-1H-pyrido[4,3-b]carbazole; attempts to synthesise 2,3,4,10-tetrahydro-5-hydroxy-2-methyl-1H-pyrido[3,4-b]carbazole

Abstract

The synthesis of 1-methyl-3-(dimethylaminomethyl)indol-2-yl, 3-(dimethylaminomethyl)indol-2-yl, 2-(dimethylaminomethyl)indol-3-yl, and 2-methoxymethylindol-3-yl 1,2,5,6-tetrahydro-1-methylpyridin-4-yl ketones is described. Although each of these could be isomerised to the corresponding cyclic enamine (2-piperideine), only in the first case could the result of intramolecular β-alkylation of the enamine be obtained, i.e. 2,3,4,6-tetrahydro-5-hydroxy-2,6-dimethyl-1H-pyrido[4.3-b]carbazole (9a).