Carbonyl-Enamine a New Mode for Azepine Ring Closure: Synthesis and Characterization of Pyrazino{2,3-c}azepine, as a New Ring System

Pyrazino{2,3-c}azepine and azepino{3,4-b}quinoxaline represent new ring systems and were prepared by fusing either of pyrazine ring onto azepine derivative or vice versa. Intramolecular 1,7-carbonyl-enamine cyclization was studied as a new mode for azepine ring closure. Various examples and reaction conditions were studied for this ring closure.