Catalytic Desymmetrizing Baeyer–Villiger Oxidation of Quaternary Carbon-Containing Cyclobutane-1,3-diones

The first highly enantioselective Baeyer-Villigeroxidationof quaternary carbon-containing cyclobutane-1,3-diones using chiralphosphoric acid catalysis and commercially available oxidants wasreported. According to the structure of the substrates, two optimizedreaction conditions were developed to afford the corresponding chiraltetronic acid products in & LE;93% and & LE;95% ee values. Thisreaction offers the first catalytic asymmetric approach to chiral5,5-disubstituted tetronic acid derivatives. The synthetic potentialof this method has been demonstrated by the formal asymmetric synthesisof (-)-vertinolide and the first catalytic asymmetric totalsynthesis of plakinidone B.