| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1343697 | Tetrahedron: Asymmetry | 2015 | 5 Pages |
The N-Boc-protected (S)-prolinamine reacts readily with formaldehyde and diverse α-hydroxyimino ketones to give imidazole N-oxides with an enantiomerically pure N-protected (pyrrolidin-2-yl)methyl substituent. Subsequent deprotection yields the corresponding NH derivatives. Upon treatment of these products with Ac2O at room temperature, a cascade of reactions leads to optically active tricyclic products. In all these processes, the stereogenic center is preserved. In one case, the bis-heterocyclic imidazole N-oxide was transformed into the corresponding optically active imidazole-2-thione via a sulfur-transfer reaction with 2,2,4,4-tetramethylcyclobutane-1,3-dithione.
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1-{[(2S)-N-Boc-pyrrolidin-2-yl]methyl}-4,5-diphenyl-1H-imidazole 3-oxideC25H29N3O3Ee = 100%[α]D25 = −8 (c 0.625, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
1-{[(2S)-N-Boc-pyrrolidin-2-yl]methyl}-4,5-dimethyl-1H-imidazole 3-oxideC15H25N3O3Ee = 100%[α]D25 = −24 (c 0.5, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
1-{[(2S)-N-Boc-pyrrolidin-2-yl]methyl}-4-methyl-5-phenyl-1H-imidazole 3-oxideC20H27N3O3Ee = 100%[α]D25 = +99 (c 0.25, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
N-Phenyl-1-{[(2S)-N-Boc-pyrrolidin-2-yl]methyl}-5-methyl-1H-imidazole-4-carboxamide 3-oxideC21H28N4O4Ee = 100%[α]D25 = −12 (c 0.55, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
{[(2S)-Pyrrolidin-2-yl]methyl}-4,5-diphenyl-1H-imidazole 3-oxideC20H21N3OEe = 100%[α]D25 = +81 (c 0.5, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
{[(2S)-Pyrrolidin-2-yl]methyl}-4,5-dimethyl-1H-imidazole 3-oxideC10H17N3OEe = 100%[α]D25 = +53 (c 0.25, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
{[(2S)-Pyrrolidin-2-yl]methyl}-4-methyl-5-phenyl-1H-imidazole 3-oxideC15H19N3OEe = 100%[α]D25 = +58 (c 0.25, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
N-Phenyl-{[(2S)-pyrrolidin-2-yl]methyl}-5-methyl-1H-imidazole-4-carboxamide 3-oxideC16H20N4O2Ee = 100%[α]D25 = +28 (c 1.0, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
N-Phenyl-{[(2S)-pyrrolidin-2-yl]methyl}-5-methyl-2-thioxo-2,3-dihydro-1H-imidazole-4-carboxamideC16H20N4OSEe = 100%[α]D25 = +16 (c 1.0, DMSO)Source of chirality: (S)-prolineAbsolute configuration: (S)
(5aS)-2,3-Diphenyl-5a,6,7,8-tetrahydro-5H-pyrrolo[1,2-c]imidazo[1,2-a]imidazoleC20H19N3Ee = 100%[α]D25 = −35 (c 0.25, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
(5aS)-2,3-Dimethyl-5a,6,7,8-tetrahydro-5H-pyrrolo[1,2-a]imidazo[1,2-a]imidazoleC10H15N3Ee = 100%[α]D25 = −31 (c 0.4, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
(5aS)-2-Methyl-3-phenyl-5a,6,7,8-tetrahydro-5H-pyrrolo[1,2-c]imidazo[1,2-a]imidazoleC15H17N3Ee = 100%[α]D25 = −229 (c 0.25, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
N-Phenyl-[(5aS)-3-methyl-5a,6,7,8-tetrahydro-5H-pyrrolo[1,2-c]imidazo[1,2-a]imidazole]-2-carboxamideC16H18N4OEe = 100%[α]D25 = −86 (c 0.375, CH2Cl2)Source of chirality: (S)-prolineAbsolute configuration: (S)
