Catalytic enantioselective approach to the stereodivergent synthesis of (+)-lasubines I and II

[GRAPHICS] A concise and efficient approach to the stereodivergent synthesis of (+)-lasubines I and II is described. The key common intermediate is a chiral N-sulfonyl 2,3-dihydropyridone obtained by a novel Cu-catalyzed asymmetric formal aza-Diels-Alder reaction between N-tosyl aldimines and Danishefsky's diene.