A New Approach to the Benzopyridoxepine Core by Metal Mediated Intramolecular Biaryl Ether Formation

Abstract

This paper presents a concise synthesis of the novel [1,3]dioxo[d]benzoxepino[2,3-c]-6-bromopyridine 1. The benzopyridoxepine core has been obtained by intramolecular coupling of a benzopyridylethene that is in turn obtained from the Wittig reaction. Thus, the synthesis was accomplished in a very good yield by implementation of an intramolecular palladium-catalyzed biaryl ether formation (Buchwald-Hartwig type reaction). An alternative approach based on the copper-mediated C-O bond formation (intramolecular Ullmann reaction) was not successful.