Cacalolides from Senecio madagascariensis

14-Isovaleryloxy-O-methyl- 1,2-dehydrocacalol( 1) and cycloart-23-ene-3,25- diol, beta -sitosterol, and stigmasterbl, along with five new cacalolides, 1-hydroxy-2-methoxy-1,2,3,4-dehydro-6-de (2), 1-hydroxy-2-methoxy-1,2,3,4-d ehydrocacal (3), 1,2-dimethoxy-1,2,3,4-dehydro-6-dehydrox (4), 1,2-dimethox y-1,2,3,4-dehydrocacalone (5), and 2-methoxy-O-methyl-l-oxo-2,3-dehydrocaca (6), were isolated from Senecio madagascariensis collected from Colombia. The structures of the new compounds were determined using one- and two-dime nsional NMR techniques. In addition, the structure of 2 was corroborated by derivatizations and single-crystal X-ray diffraction studies.