A New Transformation of 2H-Pyran-2-one ring: First Synthesis of Pyridazino[4,3-c]azepines and their Oxidation with Thallium(III) Nitrate or Copper(II) Acetate - Kafka, Stanislav; Trebe, Polonca; Polanc, Slovenko; Koevar, Marijan (Synlett, 2000)