Preparation of the title compounds was carried out according to General Method 8. 3-Chlorophenylhydrazine hydrochloride (5 g, 27.9 mmol), 1-bromo-2-cyclohexylethane (4.37 ml, 27.9 mmol), triethyl amine (11.66 ml, 83.7 mmol) and N-methyl-4-piperidone hydrochloride (4 g, 27.9 mmol) were combined in ethanol (30 ml) to obtain 9-chloro-5-(2-cyclohexylethyl)-2,3,4,5-tetrahydro-2-methyl-1H-pyrido[4,3-b]indole and 7-chloro-5-(2-cyclohexylethyl)-2,3,4,5-tetrahydro-2-methyl-1H-pyrido[4,3-b]indole after on purification on silica gel (230-400 mesh) chromatography eluting with acetone-hexane gradient. The free base was converted into its oxalate salt by treatment of oxalic acid (1 equiv.) in anhydrous THF.
