合成路线1

5) The cyclization of 4-phthalimidocyclohexanone (XIV) with 4-hydrazinobenzamide (XV) in relfuxing acetic acid gives 3-phthalimido-1,2,3,4-tetrahydro-9H-carbazole-6-carboxamide (XVI), which is treated with hydrazine in methanol yielding 3-amino-1,2,3,4-tetrahydro-9H-carbazole-6-carboxamide (XVII) as a racemic mixture. Reaction of (XVII) with di-tert-butyl dicarbonate gives the corresponding carbamate that is resolved by chiral HPLC in hexane/ethanol to give (XVIII). The hydrolysis of (XVIII) with HCl in dioxane affords the enantiomerically pure (R)-amine (XIX) (1-3). The reductoalkylation of (XIX) with benzaldehyde and NaBH3CN yields the corresponding benzylamine (XX), which is methylated with formaldehyde and NaBH3CN to the N-benzyl-N-methylamine (XXI). Finally, this compound is debenzylated by hydrogenation as usual. 6) The monomethylation of (XIX) can also be performed by its reaction with carbon disulfide and dicyclohexylcarbodiimide (DCC) in pyridine to give the expected isothiocyanato (XXII), which is finally reduced with NaBH4 in ethanol.