Synthesis of novel C3 symmetric tris(thiazoline) ligands and their application in the allylic oxidation reaction

A series of novel C3 symmetric tris(thiazoline) ligands were synthesized from trimethyl nitrilotriacetate and an enantiomerically pure amino alcohol via an efficient route. Compound 7a showed moderate to good catalytic enantioselectivity for the asymmetric allylic oxidation of cycloalkenes.

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N,N′,N″-Tris[(1S)-(2-TBDMSO-1-phenylethyl-)]nitrilotriacetamideC48H78N4O6Si3
• Ee = 100%
• [α]D25=+30.0 (c 0.50, CH2Cl2)
• Source of chirality: l-amino alcohol
• Absolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-benzylethyl-)]nitrilotriacetamideC51H84N4O6Si3Ee = 100%[α]D25=+74.4 (c 0.67, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-iso-propylethyl-)]nitrilotriacetamideC39H85N4O6Si3Ee = 100%[α]D25=-38.1 (c 1.50, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-iso-butylethyl-)]nitrilotriacetamideC45H97N4O6Si3Ee = 100%[α]D25=-38.8 (c 1.0, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-phenylethyl-)]nitrilotri(thio-acetamide)C48H78N4O3S3Si3Ee = 100%[α]D25=+35.6 (c 0.50, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-benzylethyl-)]nitrilotri(thio-acetamide)C51H85N4O3S3Si3Ee = 100%[α]D25=+103.0 (c 0.63, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-iso-propylethyl-)]nitrilotri(thio-acetamide)C39H85N4O3S3Si3Ee = 100%[α]D25=-105.0 (c 0.50, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

N,N′,N″-Tris[(1S)-(2-TBDMSO-1-iso-butylethyl-)]nitrilotri(thio-acetamide)C42H91N4O3S3Si3Ee = 100%[α]D25=-62.8 (c 1.0, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

Tri{[2-(4S)-(4-phenyl-1,3-thiazolinyl)] methyl} amineC30H30N4S3Ee = 100%[α]D25=+126.0 (c 0.25, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

Tri{[2-(4S)-(4-benzyl-1,3-thiazolinyl)] methyl} amineC33H36N4S3Ee = 100%[α]D25=+120.0 (c 0.30, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

Tri{[2-(4S)-(4-i-propyl-1,3-thiazolinyl)] methyl} amineC21H36N4S3Ee = 100%[α]D25=-65.0 (c 0.30, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)

Tri{[2-(4S)-(4-i-butyl-1,3-thiazolinyl)] methyl} amineC24H42N4S3Ee = 100%[α]D25=-95.0 (c 0.20, CH2Cl2)Source of chirality: l-amino alcoholAbsolute configuration: (S)