New synthesis of diazepino[3,2,1-ij]quinoline and pyrido[1,2,3-de] quinoxalines via addition-elimination followed by cycloacylation

Abstract

This paper describes a convenient and efficient synthesis of new fused tricyclic diazepino[3,2,1-ij] quinolines and substituted pyrido[1,2,3-de]quinoxalines. o-Phenylenediamines are transformed in the tricycle nucleus in only a few-step synthetic sequence to produce ethyl 2,8-dioxo-1,2,3,4-tetrahydro-8H [1,4]diazepino[3,2,1-ij]quinoline-7-carboxylate, ethyl 8-oxo-1,2,3,4-tetrahydro-8H-[1,4]diazepino[3,2,1-ij] quinoline-7-carboxylate and ethyl 2,7-dioxo-2,3-dihydro-1H,7H-pyrido[1,2,3-de]quinoxaline-6-carboxylate. The method is economical and simple to perform