Copper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic enones

It is no longer necessary to use dialkylzinc reagents to obtain enantioselectivities >95% in the copper-catalyzed asymmetric conjugate addition of organometallic compounds to cyclic enones. We now report how this can be accomplished by using inexpensive and readily available Grignard reagents. Screening of bidentate ligands provided outstanding results with copper complexes of commercially available chiral ferrocenyl-based diphosphines, in particular TaniaPhos and JosiPhos derivatives. These catalysts tolerate a range of Grignard reagents and different cyclic enones as substrates, leading to high regioselectivities and unprecedented enantioselectivities. Moreover, the reactions are successful with moderate catalyst loading (5 mol %) under mild conditions and in the absence of additives

Enantioselective copper-catalyzed conjugate addition to trisubstituted cyclohexenones: construction of stereogenic quaternary centers

Trimethyl- and triethylaluminum undergo enantioselective conjugate addition to 3- and 2-substituted cyclohexenones in the presence of catalytic amounts of a Cu salt and a phosphoramidite ligand L* (see scheme). Thus, chiral quaternary centers can be built with up to 96.6 % ee. Functionalized enones lead to bicyclic structures by a subsequent aldol reaction