Synthesis of Polycyclic-fused Heterocycles Combining Both Quinoline Ring and Benzoxepine Framework in A Single Molecule

Abstract

A simple and facile synthesis of polycyclic-fused 10-benzoyl-benzo[6,7]oxepino[3, 4-b]quinolin-13(6H)-ones(5) is described, involving the one-pot synthesis of 6-benzoyl-2-(phenoxymethyl)quinoline-3-carboxylicacids (4) between ethyl 6-benzoyl-2- (chloromethyl)quinoline-3-carboxylate (3) with substituted phenols followed by their intramolecular Friedel-Crafts acylation reaction under the treatment with polyphosphoric acid (PPA). The required starting compound 3 was efficiently synthesized by the direct cyclization of 4-benzoylaniline (1) with 4-chloro-acetoacetic acid ester (2) through the treatment with Vilsmeiere reagent. The methodology offers easy access to tetracyclic-fused benzoxepinoquinoline system in good yields.