title: Total synthesis of dehydroaltenuene A. Revision of the structure and total synthesis of dihydroaltenuene B.
abstract: Total synthesis of alternaria toxins starting from previously synthesized altenuene (3) and isoaltenuene (4) is described. Dihydroaltenuene B (9) was prepared by hydrogenation of 3, and the non-natural epimer 3-epi-dihydroaltenuene A was obtained analogously from 4. Inspection of the spectroscopic data for 9 revealed that the originally proposed structure was in error. A revised structure (11), unambiguously proven by total synthesis, is reported herein. Oxidation of 4 with oxygen in the presence of palladium(II) acetate as catalyst led to the formation of dehydroaltenuene A (8), while oxidation of 3 using identical conditions yielded ent-dehydroaltenuene B (ent-9). Oxidation of 4 with manganese(IV) oxide furnished dehydroaltenusin (12), although only impure material was obtained in low yield.
authors: Institut fur Organische Chemie, Universitat Karlsruhe, Karlsruher Institut fur Technologie, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
authors: Martina
authors: M
authors: Altemöller
authors: Joachim
authors: J
authors: Podlech
mesh_terms: D000528:Alternaria / Q000737:chemistry; D002384:Catalysis; D006865:Hydrogenation; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D007783:Lactones; C543756:dehydroaltenuene A; C543757:dihydroaltenuene B; C040005:altenuene; D010165:Palladium