合成路线1

Indole (I) is protected as the indole N-carboxylate (II) by treatment of its lithio derivative with carbon dioxide gas in cold THF. Subsequent metalation with tert-butyllithium, followed by addition to cyclopentanone (III) gives rise to the carbinol adduct (IV). Dehydration of (IV) under acidic conditions furnishes 2-(1-cyclopentenyl)indole (V). Diels-Alder condensation of (V) with maleimide (VI) at 190 C provides the pentacyclic system (VII). Further dehydrogenation of (VII) employing DDQ leads to the fused carbazole compound (VIII). Regioselective halogenation of (VIII) at position 3 by means of NBS yields the corresponding aryl bromide (IX). Then, displacement of the bromide group of (IX) with either CuCN or Zn(CN)2 produces nitrile (X). This is finally reduced to the primary amine by catalytic hydrogenation in the presence of Raney nickel and ammonia.