Conversion of Natural Narciclasine to Its C-1 and C-6 Derivatives and Their Antitumor Activity Evaluation: Some Unusual Chemistry of Narciclasine oleh Juana Goulart Stollmaier, Jared Thomson, Mary Ann Endoma-Arias, Razvan Simionescu, Alexandra Vernaza, Nakya Mesa-Diaz, Mitchell Smith, Liqin Du, Alexander Kornienko, Tomas Hudlicky