Substrate-Controlled Regioselective Cascade Reactions of Deconjugated Butenolides and Cinnamaldehydes: Access to Structurally Diverse Spirobutenolides.

Two different cascade pathways to access spirobutenolides were achieved based on the substrate-controlled regioselectivity of deconjugated butenolides. A new class of functional deconjugated butenolides was designed and exhibited superior γ-regioselectivity in the vinylogous Michael/Michael cascade reactions with cinnamaldehydes. The aryl-substituted deconjugated butenolides and cinnamaldehydes underwent a Michael/Michael/aldol/dehydration cascade process induced by double α-regioselectivities. Both conjugated and deconjugated spirobutenolides could be obtained in good yields with excellent enantioselectivities.