Enantioselective C–H carbene insertions with homogeneous and immobilized copper complexes

Abstract

The efficiency of chiral bis(oxazoline)- and azabis(oxazoline)-copper complexes in the enantioselective carbene insertion into C–H bonds of cyclic ethers in homogeneous phase strongly depends on the structure of the substrate. The immobilization on laponite clay by electrostatic interactions not only allows the recovery and reuse of the heterogeneous catalysts, but in some cases also improves enantioselectivity and overall chemoselectivity, making possible reactions that do not take place or lead to low yields in solution, even with the commonly used Rh₂[S-DOSP]₄ catalyst.