| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1349257 | Tetrahedron: Asymmetry | 2010 | 19 Pages |
The synthesis of a range of C2-symmetric imidazolinium salts from (1R,2R)-cyclohexane-1,2-diamine, and an evaluation of the reactivity and asymmetric induction of the derived NHCs as catalysts for the asymmetric synthesis of β-lactams, is reported. In this series, optimal enantioselectivity (up to 70% ee) is observed using N-benzyl or N-1-naphthylmethyl-substituted NHCs, consistent with a chiral relay effect operating to dictate the stereochemical outcome of this reaction.
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(3aR,7aR)-1,3-Dimethyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC9H17BF4N2Ee 100%[α]D20=-144.2 (c 1.1, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Diethyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC11H21 BF4N2Ee 100%[α]D20=-107.8 (c 1.1, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Dineopentyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC17H33BF4N2Ee 100%[α]D20=-22.0 (c 1.0, CH2Cl2)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(4-methoxybenzyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC23H29BF4N2O2Ee 100%[α]D20=-85.5 (c 1.1, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(4-(trifluoromethyl)benzyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC23H23BF7N2Ee 100%[α]D20=-30.2 (c 1.1, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(naphthalene-1-ylmethyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC29H29BF4N2Ee 100%[α]D20=-71.2 (c 0.9, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(naphthalene-2-ylmethyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC29H29BF4N2Ee 100%[α]D20=-82.9 (c 1.1, CH2Cl2)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(2,4,6-trimethylbenzyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC27H37BF4N2Ee 100%[α]D20=-21.5 (c 0.6, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Dibenzyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium chlorideC21H25BF4N2Ee 100%[α]D20=-62.2 (c 1.0, CHCl3)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Diphenyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC19H21BF4N2Ee 100%[α]D20=+66.2 (c 0.6, MeOH)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Di-o-tolyl-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC21H27BF4N2Ee 100%[α]D20=+47.1 (c 0.5, CH2Cl2)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(3aR,7aR)-1,3-Bis(2-isopropylphenyl)-3a,4,5,6,7,7a-hexahydro-1H-benzo[d]imidazol-3-ium tetrafluoroborateC25H35BF4N2Ee 100%[α]D20=+20.6 (c 0.5, CH2Cl2)Source of chirality: (1R,2R)-trans-cyclohexane-1,2-diammonium (S)-tartrateAbsolute configuration: (R,R)
(S)-3,3-Diphenyl-4-(2-furanyl)-1-tosylazetidin-2-oneC26H21NO4SEe 70%[α]D20=+28.1 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)
(R)-3,3,4-Triphenyl-1-tosylazetidin-2-oneC26H23NO3SEe 56%[α]D20=+15.8 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)
(R)-3,3-Diphenyl-4-(4-bromophenyl)-1-tosylazetidin-2-oneC28H22NO3SBrEe 55%[α]D20=+14.7 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)
(R)-3,3-Diphenyl-4-(2-phenylvinyl)-1-tosylazetidin-2-oneC30H25NO3SEe 42%[α]D20=+59.6 (c 0.5, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)
(R)-3,3-Diphenyl-4-(4-methoxyphenyl)-1-tosylazetidin-2-oneC29H25NO4SEe 23%[α]D20=+2.9 (c 0.6, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)
(3R,4S)-3-Ethyl-3,4-diphenyl-1-tosylazetidin-2-oneC24H23NO3SEe 29%[α]D20=-14.0 (c 0.3, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4S)
(3R,4R)-3-Ethyl-4-(furan-2-yl)-3-phenyl-1-tosylazetidin-2-oneC22H21NO4SEe 26%[α]D20=+35.6 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4S)-3-Ethyl-4-(naphthalen-1-yl)-3-phenyl-1-tosylazetidin-2-oneC28H25NO3SEe 12%[α]D20=-0.3 (c 0.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4S)
(3R,4S)-3-Ethyl-4-(naphthalen-2-yl)-3-phenyl-1-tosylazetidin-2-oneC28H25NO3SEe 54%[α]D20=-145.9 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4S)
