We have developed a series of new chiral thiophosphorodiamide ligands derived from (1R,2R)-(+)-1,2-diphenylethylenediamine, which are the structural relatives of thioureas. An investigation into their catalytic properties in asymmetric additions of diethylzinc to aldehydes has shown that N,N,N′,N′-tetra-substituted chiral thiophosphorodiamides can give (R)-secondary alcohols with up to 98% yield and 98% ee, while N,N′-di-substituted chiral thiophosphorodiamides give (S)-secondary alcohols with up to 99% yield and 97% ee values. The enantioselectivity switch is highly efficient with a broad substrate scope. We have also proposed hypothetical reaction pathways, which result in an enantioselectivity switch.(1R,2R)-N-Phthaloyl-1,2-diphenylethylenediamineC22H18N2O2[α]D31=+80.5 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N,N-Dimethyl-N′-phthaloyl-1,2-diphenylethylenediamineC24H22N2O2[α]D31=-89.5 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N,N-Diethyl-N′-phthaloyl-1,2-diphenylethylenediamineC26H26N2O2[α]D31=-213.0 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)2-[(1R,2R)-1,2-Diphenyl-2-(pyrrolidin-1-yl)ethyl]-2,3-dihydro-1H-isoindole-1,3-dioneC26H24N2O2[α]D31=-111.1 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)2-[(1R,2R)-1,2-Diphenyl-2-(piperidin-1-yl)ethyl]-2,3-dihydro-1H-isoindole-1,3-dioneC27H26N2O2[α]D31=-110.9 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Ethyl-N′-phthaloyl-1,2-diphenylethylenediamineC24H22N2O2[α]D31=+32.2 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Isopropyl-N′-phthaloyl-1,2-diphenylethylenediamineC25H24N2O2[α]D31=+16.5 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Pentyl-N′-phthaloyl-1,2-diphenyl ethylenediamineC27H28N2O2[α]D31=+19.0 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Ethyl-N-methyl-N′-phthaloyl-1,2-diphenylethylenediamineC25H24N2O2[α]D31=-135.5 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Isopropyl-N-methyl-N′-phthaloyl-1,2-diphenylethylenediamineC26H26N2O2[α]D31=-104.7 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Pentyl-N-methyl-N′-phthaloyl-1,2-diphenylethylenediamineC28H30N2O2[α]D31=+107.1 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Acetyl-N′-phthaloyl-1,2-diphenylethylenediamineC24H20N2O3[α]D31=+9.9 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Boc-N′-phthaloyl-1,2-diphenylethylenediamineC27H26N2O4[α]D31=-29.2 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)(1R,2R)-N-Cbz-N′-phthaloyl-1,2-diphenylethylenediamineC30H24N2O4[α]D31=+23.8 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-2-(Dimethylamino)-1,2-diphenylethyl]({[(1R,2R)-2-(dimethylamino)-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amineC38H43N4PS[α]D31=+141.0 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-2-(Diethylamino)-1,2-diphenylethyl]({[(1R,2R)-2-(diethylamino)-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amineC42H51N4PS[α]D31=+69.7 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-1,2-Diphenyl-2-(pyrrolidin-1-yl)ethyl]({[(1R,2R)-1,2-diphenyl-2-(pyrrolidin-1-yl)ethyl]amino}(phenyl)thiophosphoryl)amineC42H47N4[α]D31=+67.1 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-1,2-Diphenyl-2-(piperidin-1-yl)ethyl]({[(1R,2R)-1,2-diphenyl-2-(piperidin-1-yl)ethyl]amino}(phenyl)thiophosphoryl)amineC44H51N4PS[α]D31=+118.4 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-2-[Ethyl(methyl)amino]-1,2-diphenylethyl]({[(1R,2R)-2-[ethyl(methyl)amino]-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amineC40H47N4PS[α]D31=+140.2 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-2-[Methyl(propan-2-yl)amino]-1,2-diphenylethyl]({[(1R,2R)-2-[methyl(propan-2-yl)amino]-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amineC42H51N4PS[α]D31=+140.2 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)[(1R,2R)-2-[Methyl(pentyl)amino]-1,2-diphenylethyl]({[(1R,2R)-2-[methyl(pentyl)amino]-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amineC46H59N4PS[α]D31=+104.6 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)N-[(1R,2R)-2-[({[(1R,2R)-2-Acetamido-1,2-diphenylethyl]amino}(phenyl)thiophosphoryl)amino]-1,2-diphenylethyl]acetamideC38H39O2N4PS[α]D31=+65.0 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)tert-Butyl N-[(1R,2R)-2-[({[(1R,2R)-2-{[(tert-butoxy)carbonyl]amino}-1,2-diphenyl ethyl]amino}(phenyl)thiophosphoryl)amino]-1,2-diphenylethyl]carbamateC44H51O4N4PS[α]D31=+30.8 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)Benzyl N-[(1R,2R)-2-[({[(1R,2R)-2-{[(benzyloxy)carbonyl]amino}-1,2-diphenyl ethyl]amino}(phenyl)thiophosphoryl)amino]-1,2-diphenylethyl]carbamateC50H47O4N4PS[α]D31=+28.8 (c 1.00, CH2Cl2)Source of chirality: (1R,2R)-(+)-1,2-diphenylethylenediamineAbsolute configuration: (1R,2R)