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

Article abstract of DOI:10.1002/adsc.201201041

A chiral quaternary ammonium amide was generated in situ from N,O-bis(trimethylsilyl)acetamide (BSA) as non-nucleophilic Bronsted 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 (5H)-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. Copyright