It uses a catalyst containing either (+)- or (-)-diethyl tartrate to form the chiral epoxide in greater than 90 % enantiomeric excess.
The oxidizing agent is tert-butyl hydroperoxide.
The catalyst is prepared from titanium tetra(isopropoxide), #"Ti"["OCH"("CH"_3)_2]_4#.
It binds the hydroperoxide, the allylic alcohol group, and the chiral tartrate ligand through the oxygen atoms.
A "simplified" Jmol image of the complex (below) shows how an #"O"# atom of the hydroperoxide is preferentially pointed towards one face of the alkene.
(Adapted from chemtube3d)