A simple and efficient method for constructing azocino[4,3-b]indole

A new synthetic procedure has been developed to prepare the biologically important azocino[4,3-b]indole via the tetrafluoro-1,4-benzoquinone (TFB)-mediated cyclization of a tetrahydrocarbazole derivative bearing an amide side chain at the C-2 position. For the first time, this strategy is based on a different method for the C-2 position of the tetrahydrocarbazole for the synthesis of methanoazocino[4,3-b]indole. The notable features of this protocol include its operational simplicity and high reaction yields. Furthermore, the structures of all the presently synthesized compounds were confirmed using spectroscopic methods (1H NMR, 13C NMR, FT-IR).