Investigations on the iron-catalyzed asymmetric sulfide oxidation

The development of an enantioselective sulfide oxidation involving a chiral iron catalyst and aqueous hydrogen peroxide as oxidant is described. In the presence of a simple carboxylic acid, or a carboxylate salt, the reaction affords sulfoxides with remarkable enantioselectivities up to 96% ee) in moderate to good yields. The influence of the structure of the 4.8) occurs, which, however, plays only additive on the reaction outcome is re- a negligible role in the overall enantioported. In the sulfoxide-to-sulfone oxi- selective process. Furthermore, a posidation a kinetic resolution (with s= tive nonlinear relationship between the ee of the product and that of the catalyst has been found. On the basis of these observations, a possible catalyst structure is proposed.