Chiral Quaternary Ammonium Aryloxide/ N,O ‐Bis(trimethyl‐ silyl)acetamide Combination as Efficient Organocatalytic System for the Direct Vinylogous Aldol Reaction of ( 5H )‐Furan‐2‐one Derivatives

A chiral quaternary ammonium amide was generated in situ from N,O ‐bis(trimethylsilyl)acetamide (BSA) as non‐nucleophilic Brønsted base precursor and the combination of chiral quaternary ammonium halide/sodium aryloxide as chiral Lewis base. This system was applied to an anti ‐selective organocatalytic direct vinylogous aldol (ODVA) reaction of (5 H )‐furan‐2‐one derivatives with aldehydes. Several 5‐(1′‐hydroxy)‐γ‐butenolides were obtained in good diastereomeric ratios (up to 95/5) and excellent enantioselectivities (up to 94%) with both aliphatic or (hetero)aromatic aldehydes, so providing a rare example of general and efficient conditions for the ODVA reaction.