Imidazolinium sulfonate and sulfamate zwitterions as chiral solvating agents for enantiomeric excess calculations

The synthesis of enantiopure unsymmetrical N-heterocyclic based zwitterions incorporating imidazolinium and alkylsulfonate or sulfamate groups is described. The desired compounds were prepared in good yields from 1,3-propanesultone or cyclic sulfamidates and imidazolines. The imidazolinium based zwitterions proved to be versatile chiral solvating agents for Mosher’s acid, alcohols, cyanohydrins, amino alcohols, nitro alcohols, thiols, and carboxylic acids with very high shifts in the 1H and 19F NMR.

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(4R,5R)-4,5-Diphenyl-1-(2,4,6-trimethylbenzyl)-1H-imidazolineC25H26N2ee = 100%[α]D22=+17.8 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (4R,5R)

(1R,2R)-1,2-Diphenyl-N-(o-tolyl)ethane-1,2-diamineC14H32N2ee = 100%[α]D22=+93.4 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (1R,2R)

3-((4R,5R)-4,5-Diphenyl-1-(2,4,6-trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)propane-1-sulfonateC28H33N2O2See = 100%[α]D22=+105.6 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (4R,5R)

(S)-2-((4R,5R)-4,5-Diphenyl-1-(2,4,6-trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)(methyl)pyrrolidine-1-sulfonateC30H35N3O3See = 100%[α]D22=+129.7 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (S)(4R,5R)

((1R,2R)-1-((4S,5S)-4,5-Diphenyl-1-(2,4,6-trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)-1-phenylpropan-2-yl)(methyl)sulfamateC35H40N3O3See = 100%[α]D22=-117.8 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (1R,2R)(4S,5S)

(S)-2-(((4S,5S)-4,5-Diphenyl-1-(2,4,6-trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)methyl)pyrrolidine-1-sulfonateC30H35N3O3See = 100%[α]D22=-13.5 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (S)(4S,5S)

(S)-2-((1-(2,4,6-Trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)ethyl)pyrrolidine-1-sulfonateC18H27N3O3See = 100%[α]D22=+40.3 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (S)

Methyl((1R,2R)-1-phenyl-1-(1-(2,4,6-trimethylbenzyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)propan-2-yl)sulfonateC23H32N3O3See = 100%[α]D22=+35.5 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (1R,2R)

3-((4R,5R)-4,5-Diphenyl-1-(o-tolyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)propane-1-sulfonateC25H27N2O3See = 100%[α]D22=+262.2 (c 1, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (4R,5R)

((1R,2R)-1-((4R,5R)-4,5-Diphenyl-1-(o-tolyl)-4,5-dihydro-1H-imidazol-3-ium-3-yl)-1-phenylpropan-2-yl)(methyl)sulfamateC32H33N3O3See = 100%[α]D22=+183 (c 0.5, CH2Cl2)Source of chirality: chiral poolAbsolute configuration: (1R,2R)(4R,5R)