Sipandinolide: A Butenolide Including a Novel Type of Carbon Skeleton from Siparuna andina - Jenett-Siems, Kristina; Siems, Karsten; Jakupovic, Jasmin; Solis, Pablo N; Gupta, Mahabir P; Mockenhaupt, Frank P; Bienzle, Ulrich; Eich, Eckart (Planta Medica, 2000)