New chiral amino-phosphoramidite and bisphosphoramidite ligands derived from (R, R)-1,2-diaminocyclohexane: application in Cu-catalyzed asymmetric conjugate addition of diethylzinc to 2-cyclohexenone

Abstract New bidentate amino-phosphoroamidite and diphosphoroamidite ligands derived from inexpensive ( R , R )-1,2-diaminocyclohexane have been synthesized and screened in the Cu-catalyzed asymmetric conjugate addition of Et 2 Zn to 2-cyclohexenone. The highest 74% ee value was reached with the N , N ′-dimethyl substituted P , N -ligand and Cu(OAc) 2 ·H 2 O.