Recyclization of 2-Imino-2H-1-benzopyrans with Nucleophilic Reagents - Reaction of 2-Iminocoumarin-3-carboxamides with 2-Aminothiophene-3-carboxamides - Kovalenko, Sergiy M; Vlasov, Sergiy V; Chernykh, Valentin P (Synthesis, 2006)