Epoxidation of Acyclic chiral Allylic Alcohols with Peroxy Acids: Spiro or Planar Butterfly Transition Structures? A Computational DFT Answer.

The mechanism of the epoxidation of two chiral allylic alcohols, i.e., 3-methyl-3-buten-2-ol and (Z)-3-penten-2-ol, with peroxyformic acid has been investigated by locating 20 transition structures with the B3LYP/6-31G* method. The geometry of all TSs substantially conforms to a spiro (i.e., with the peroxy acid plane almost perpendicular to the CdC bond axis) butterfly orientation of the reactants while no TS resembles, even loosely, the planar butterfly structure.