A New Route to Ring-Fused Pyrazines: Imidazo[4,5-b]Quinoxalines by a Simple Oxidation-Annulation Sequence - Herzog, Svenja; Buehrdel, Gunther; Beckert, Rainer; Klimas, Susann; Würthwein, Ernst-Ulrich; Grimme, Stefan; Görls, Helmar (Synthesis, 2009)