Studies on the synthesis of (-)-spinosyn a: application of the steric directing group strategy to transannular Diels-Alder reactions.
A highly diastereoselective and enantioselective synthesis of the decahydro-as-indacene nucleus 12 of (-)-spinosyn A (1) is reported. By implementing the steric directing group strategy, tricyclic lactone 37 was produced from a remarkably diastereoselective transannular Diels-Alder reaction of lactone 9. The tricyclic core of the natural product was then obtained by using an Ireland-Claisen ring contraction of 37. Reversal of the order of these two steps resulted in an almost complete loss of diastereoselectivity.
Frank
Scott A
SA
Department of Chemistry, University of Michigan, Ann Arbor 48109-1055, USA.
Roush
William R
WR
D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000138:chemical synthesis*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D003500:Cyclization; D006571:Heterocyclic Compounds / Q000737:chemistry*; D018942:Macrolides; D015394:Molecular Structure
D000900:Anti-Bacterial Agents; D006571:Heterocyclic Compounds; D018942:Macrolides; C114883:spinosyn A