Stereoselective dioxygenation of enoates

Article abstract of DOI:10.1016/S0040-4020(01)85363-1

The auxiliary-directed reaction of singlet oxygen with tiglate esters furnishes an asymmetric synthesis of 3-hydroperoxy-2-methylidene butenoates. Although previous reports have suggested that s-cis enoate conformers undergo preferential oxygenation relative to the s-trans conformers, our results suggest that both conformers are reactive and that the modest stereoselectivity is based upon a conformational equilibrium favoring the s-trans conformer.