Novel chemical agents are described herein. More a ligand of general Formula I: ##STR00001## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4, are independently selected from the group consisting of hydrogen, halogen, hydroxy, C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10 alkenyl, C.sub.2-C.sub.10 alkynyl, C.sub.1-C.sub.10 alkoxy, C.sub.1-C.sub.10 alkylthio, C(O)R.sub.5, C(O)OR.sub.5, C(O)NHR.sub.5, Si(R.sub.5).sub.3, benzyl and aryl; X is selected from the group consisting of Cl, Br, I, OR.sub.6, O-Prot, OPR.sub.6, P(R.sub.6).sub.2, NHR.sub.6, N(R.sub.6).sub.2, NHCSNHR.sub.6, NHCONHR.sub.6 and SR.sub.6; and R.sub.5 and R.sub.6 are independently selected from the group consisting of hydrogen, C.sub.1-10 alkyl, C.sub.2-10 alkenyl, C.sub.2-10 alkynyl, C.sub.1-10 alkoxy, phenyl, and aryl. These ligands are useful in asymmetric reactions as well as in asymmetric synthesis of molecules of biological interest.