The preparation of new enantiopure imidazolinium salts and their evaluation as catalysts and shift reagents

A series of new chiral imidazolinium salts were prepared and tested as catalysts. It was possible to show that bis-imidazolinium salts had a higher reactivity than mono-imidazolinium salts. In addition a chiral discrimination of the bis-imidazolinium salts with the potassium salt of racemic Mosher’s acid was proven by NMR studies.

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(−)-(4S,5S)-1,3-Dimethyl-2-(2-((4S,5S)-1,3-dimethyl-4,5-diphenylimidazolidin-2-yl)phenyl)-4,5-diphenylimidazolidineC40H42N4Ee = 99%[α]D22=-89.8 (c 0.44, CHCl3)Source of chirality: resolutionAbsolute configuration: (S,S)

(+)-(3aR,7aR)-Octahydro-2-(2-((3aR,7aR)-octahydro-1,3-dimethyl-1H-benzo[d]imidazol-2-yl)phenyl)-1,3-dimethyl-1H-benzo[d]imidazoleC24H28N4Ee = 99%[α]D22=+103.6 (c 1.48, CHCl3)Source of chirality: resolutionAbsolute configuration: (R,R)

(−)-(4S,5S)-1,3-Dimethyl-2-(2-((4S,5S)-1,3-dimethyl-4,5-diphenylimidazolidin-2-yl)phenyl)-4,5-diphenylimidazolinium bis-tetrakis(3,5-bis(trifluoromethyl)phenyl)borateC104H64N4F48B2Ee = 99%[α]D22=-25 (c 0.45, acetone)Source of chirality: resolutionAbsolute configuration: (S,S)

(−)-(4R,5R)-1,3-Dimethyl-2-(2-((4R,5R)-1,3-dimethyl-4,5-diphenylimidazolidin-2-yl)phenyl)-4,5-diphenylimidazolinium bis-tetrakis(3,5-bis(trifluoromethyl)phenyl)borateC88H60N4F48B2Ee = 99%[α]D22=-5.9 (c 0.67, acetone)Source of chirality: resolutionAbsolute configuration: (R,R)