Copper-catalyzed asymmetric 1,4-additions with chiral ligands

Abstract

The chiral binaphthyl phosphorusamidite lignads were synthesized from chiral binaphthol and $C_2$-symmetric cyclic amines through phosphorus ligands. These chiral ligands provided high enantioselectivities in Cu-catalyzed Enantioselective 1,4-addition. Binaphthyl phosphorous amidite ligands (4 mol%) having chiral cyclic amine were examined for the enantioselective 1,4-additions of dialkylzinc reagents. The coppertriflate (2 mol%) catalyzed Michael additions to various enones have been achieved in high enantiomeric excess (up to ＞ 93%). A macrocyclic enone such as precursor of R-(-)-muscone for 1,4-addition was examined. The addition of dimethylzinc to a macrocyclic 15-membered ring enone lead to optically active R-(-)-mucone, in ＞ 90% yield (up to 90% ee) in the presence of $Cu(OTf)_2$ (2 mol%) in toluene.