| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1344945 | Tetrahedron: Asymmetry | 2008 | 11 Pages |
The synthesis of γ-phenyl and γ-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%, while for the trans-isomers the ee’s ranged from 80% to 93%. The same ketodiester precursors were subjected to reduction with a series of yeasts. The absolute configuration of trans-(−)-2-pyridyl paraconic acid was assigned by means of X-ray analysis of its hydrobromide salt, while the absolute configurations of the other lactones were determined via analysis of their respective CD curves.
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Ethyl (2R,3S)-(+)-5-oxo-2-phenyltetrahydro-3-furancarboxylateC13H14O4Ee = 94% (by chiral HRGC)[α]D25=+10.0 (c 0.54, MeOH)Δε217 = +2.9 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3S)
Ethyl (2R,3R)-(−)-5-oxo-2-phenyltetrahydro-3-furancarboxylateC13H14O4Ee = 93% (by chiral HRGC)[α]D25=-55.3 (c 0.58, MeOH)Δε221 = −2.7 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3R)
(2S,3S)-(+)-5-Oxo-2-phenyltetrahydro-3-furancarboxylic acidC11H10O4Ee = 32% (by chiral HRGC)[α]D25=+19 (c 0.2, MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2S,3S)
Ethyl (2R,3S)-(−)-5-oxo-2-(2-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 98% (by chiral HRGC)[α]D25=-7.3 (c 0.49, MeOH)Δε215 = +2.0 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3S)
Ethyl (2R,3S)-(+)-5-oxo-2-(3-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 99% (by chiral HRGC)[α]D25=+14.7 (c 0.6, MeOH)Δε209 = +2.6 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3S)
Ethyl (2R,3S)-(+)-5-oxo-2-(4-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 99% (by chiral HRGC)[α]D25=+12.6 (c 0.35, MeOH)Δε210 = +2.0 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3S)
Ethyl (2R,3R)-(−)-5-oxo-2-(2-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 80% (by chiral HRGC)[α]D25=-52.8 (c 0.49, MeOH)Δε213 = −2.3 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3R)
Ethyl (2R,3R)-(−)-5-oxo-2-(3-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 94% (by chiral HRGC)[α]D25=-51.6 (c 0.5, MeOH)Δε215 = −1.0 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3R)
Ethyl (2R,3R)-(−)-5-oxo-2-(4-pyridyl)tetrahydro-3-furancarboxylateC12H13NO4Ee = 89% (by chiral HRGC)[α]D25=-48.7 (c 0.23, MeOH)Δε215 = −2.2 (MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3R)
Ethyl (2R,3R)-(−)-5-oxo-2-(2-pyridyl)tetrahydro-3-furancarboxylic acid hydrobromideC10H10BrNO4Ee = 80% (by chiral HRGC)[α]D25=-23.4 (c 0.47, H2O)Source of chirality: enzymatic resolutionAbsolute configuration: (2R,3R)
