The reaction of 6-cyclohexyl-3,4-dihydro-2H-carbazol-1-one (I) with 2-dibenzylaminoethyl chloride by means of phase transfer catalysis using benzyltriethylammonium chloride and sodium hydroxide in chlorobenzene gives 6-cyclohexyl-9-[2-(dibenzylamino)ethyl-3,4-dihydro-2H-carbazol-1-one (II), which is reduced with H2 over palladium bis(acetonylacetonate) and carbon to give tetrindol.