Synthesis of a benzo[b]-1,5-naphthyridine derivative as a potential constrained NK1 receptor antagonist

Article abstract of DOI:10.1016/S0040-4039(00)78224-4

A short synthesis of a cyclic constrained analogue 1 of the potent Substance P antagonist (±) CP-96345 is described. The key feature is the formation of the benzo[b]-1,5-naphthyridine system at the very last step of the synthesis through an intramolecular arylation of an amine promoted by a strong base. If the tricyclic system was synthesized first, 2-methoxy benzylation of both the nitrogen atoms occurred.