Copper-catalyzed asymmetric conjugate addition with chiral SimplePhos ligands.

SimplePhos ligands represent a novel class of monodentate chiral ligands based on a chiral amine moiety and flexible diaryl groups on the phosphorous atom. They can be easily prepared by two different pathways and they can be highly functionalised. Herein we report the copper-catalysed asymmetric conjugate addition of diethyl zinc and trialkylaluminium reagents with SimplePhos ligands, which gives high enantioselectivity with cyclic enones, acyclic enones and nitro-olefins, with up to 98.6% ee. Of particular interest is the reaction of trialkylaluminium reagents with a wide range of 3-substituted enones, thus allowing the formation of stereogenic quaternary carbon centres.