Efficient Lewis Acid Mediated Epoxyolefin Cyclizations with Pyrones as Terminators in Liquid SO2 as a Solvent - Schmidt, Dietmar; Leutbecher, Heiko; Conrad, Jürgen; Klaiber, Iris; Mika, Sabine; Greiner, Gerhard; Beifuss, Uwe (Synlett, 2007)