Industrial synthesis in mass production. Ellipticine. II. The elaboration of a new approach to GH-pyrido[4,3:b]carbazoles and analogs. B. The recovery of tetracyclic structures

Article abstract of DOI:10.1016/S0040-4020(01)80388-4

Total synthesis of modified ellipticines 1c and 1f is described from 2-chloronicotinic acid and respectively 5-methoxy-indole and 5-azaindole in 11 to 13 steps with overall yields of 11% and 18%. With respect to the numerous synthesis described in the literature, the originality of this approach resides above all in the formation of ring C in basic medium, such conditions being dictated by the presence of the pyridine A ring in the case of 1f. Both synthesis have been extrapolated to produce several kilograms of final product. The second part deals with the elaboration of tetracyclic structures from precursors.