Cu^I-Catalysed Enantioselective Alkyl 1,4-Additions to (E)-Nitroalkenes and Cyclic Enones with Phosphino-Oxazoline Ligands

Catalytic enantioselective conjugate additions of simple alkyl groups to nitroalkenes or cyclic enones that result in the formation of tertiary C–C bonds are described. For these stereoselective addition reactions, new chiral phosphino-oxazoline ligands were synthesized and used. The reactions were promoted by a Cu-based catalyst (2 mol-%), and gave the chiral products in up to 92 % yield with 95 % ee. A larger-scale synthesis was demonstrated, and the origin of the stereoselectivity was proposed based on DFT calculations.