Chemoenzymatic approaches to the decahydro-as-indacene cores associated with the spinosyn class of insecticide

The enantiopure dienes 8 and 24, which have been prepared by chemoenzymatic methods, engage in Diels-Alder cycloaddition reactions with maleic and citraconic anhydride to give adducts (e.g. 25-27) embodying the ABC-ring system associated with spinosyns A (1) and D (2).