Lewis Acid‐Catalyzed Stereoselective α‐Addition of Chiral Aldehydes to Cyclic Dienol Silanes: Aqueous Synthesis of Chiral Butenolides

The stereoselective α‐addition to cyclic dienol silanes has rarely been exploited, in contrast to the well‐studied γ‐addition of conjugated butenolides. In this study, an unprecedent catalytic Mukaiyama aldol α‐addition of 2‐trimetylsiloxy furan to optically pure aldehydes in water‐containing solvents is reported. The synthetic utility of this concept was demonstrated in the efficient synthesis of six bioactive natural products: vitexolide D, curcucomosin C, villosin, chinensine C, (+)‐coronarin E and (E)‐labda‐7,11,13‐trien‐16,15‐olid.