| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1349258 | Tetrahedron: Asymmetry | 2010 | 16 Pages |
The synthesis of a range of imidazolinium salts derived from acyclic 1,2-diamines, and an evaluation of the reactivity and asymmetric induction of the corresponding NHCs as catalysts for the asymmetric synthesis of β-lactams, is reported. An N-methyl-substituted NHC derived from (1R,2R)-1,2-diphenylethanediamine shows optimal reactivity and enantioselectivity in this series, in contrast to that observed with NHCs derived from (1R,2R)-cyclohexane-1,2-diamine.
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(S)-3-(2,5-Dimethylphenyl)-5-isopropyl-1-methyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC15H23BF4N2Ee 100%[α]D20=+38.7 (c 0.5, CHCl3)Source of chirality: l-valineAbsolute configuration: (S)
(S)-1-Benzyl-3-(2-tert-butylphenyl)-5-isopropyl-4,5-dihydro-1H-imidazolium tetrafluoroborateC23H31BF4N2Ee 100%[α]D20=-0.7 (c 1.4, CHCl3)Source of chirality: l-valineAbsolute configuration: (S)
Bis((S)-3,4-dibenzyl-1-(2-tert-butylphenyl)-4,5-dihydro-1H-imidazol-3-ium) tetrafluoroborateC27H31BF4N2Ee 100%[α]D20=+3.9 (c 1.03, CHCl3)Source of chirality: l-phenylalanineAbsolute configuration: (S)
(S)-1,3,4-Tribenzyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC24H25BF4N2Ee 100%[α]D20=+16.8 (c 0.53, MeOH)Source of chirality: l-phenylalanineAbsolute configuration: (S)
(4R,5R)-1,3-Dimethyl-4,5-diphenyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC17H19BF4N2Ee 100%[α]D20=+253 (c 0.59, CHCl3)Source of chirality: (1R,2R)-1,2-diphenylethane-1,2-diamineAbsolute configuration: (R,R)
(4R,5R)-1,3-Dibenzyl-4,5-diphenyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC29H27BF4N2Ee 100%[α]D20=+147 (c 0.25, CHCl3)Source of chirality: (1R,2R)-1,2-diphenylethane-1,2-diamineAbsolute configuration: (R,R)
(4R,5R)-4,5-Di-tert-butyl-1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium iodideC13H27IN2Ee 100%[α]D20=-63.1 (c 0.42, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R,R)
(4R,5R)-1,3-Dibenzyl-4,5-di-tert-butyl-4,5-dihydro-1H-imidazol-3-ium bromideC25H35BrN2Ee 100%[α]D20=-82.8 (c 1.09, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R,R)
(4R,5R)-1,3-Dibenzyl-4,5-di-tert-butyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC25H35BF4N2Ee 100%[α]D20=-155.2 (c 0.53, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R,R)
(4S,5S)-4,5-Diphenyl-1,3-bis((R)-1-phenylethyl)-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC31H31BF4N2Ee 100%[α]D20=-216 (c 0.98, CHCl3)Source of chirality: (1S,2S)-1,2-diphenyl-N1,N2-bis((R)-1-phenylethyl)ethane-1,2-diamineAbsolute configuration: (R,S,S,R)
(4R,5R)-4,5-Diallyl-1,3-bis((S)-1-phenylethyl)-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborateC25H31BF4N2Ee 100%[α]D20=-33.1 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S,R,R,S)
(S)-4-(Furan-2-yl)-3,3-diphenyl-1-tosylazetidin-2-oneC26H21NO4SEe 58%[α]D20=+31.2 (c 1.00, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)
(3S,4S)-3-Ethyl-4-(furan-2-yl)-3-phenyl-1-tosylazetidin-2-oneC22H21NO4SEe 33%[α]D20=-30.0 (c 0.1, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (S,S)
(R)-4-(4-Bromophenyl)-3,3-diphenyl-1-tosylazetidin-2-oneC28H22BrNO3SEe 47%[α]D20=+17.6 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)
