Use of chiral stationary phases for the chromatographic determination of enantiomeric purity and absolute configuration of some β-lactams

Pirkle, W. H.; Tsipouras, Athanasios; Hyun, Myung Ho; Hart, David J.; Lee, Chih-Shone

doi:10.1016/s0021-9673(01)90351-6

Cited by 30 publications

(9 citation statements)

References 8 publications

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“…Therefore, seven relatively stable a-lactams were chosen for this study. Previously, Pirkle-type columns 17,18 have been reported for the resolution of b-and g-lactams. Therefore, four Pirkle-type stationary phases (columns A-D, 4.6 mm 3 50 mm) were chosen for the initial part of this study.…”

Section: Resultsmentioning

confidence: 99%

The resolution of five racemic α‐lactams by HPLC

Hur

Lengyel

et al. 2007

Chirality

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The resolution of five racemic alpha-lactams (1a-d,g) using HPLC is reported. Five different Pirkle-type stationary phases were tested. The enantiomers of alpha-lactams containing the trityl group (1a-d) were separated (selectivity factors ranging from 1.08 to 1.20) using a mobile phase of hexane/2-propanol:98/2 and a stationary phase consisting of the 3,5-dinitroaniline derivative of (S)-valine with a urea linkage. Among the dialkyl-substituted alpha-lactams (1e-g), only 1,3-di-tert-butylaziridinone (1g) could be resolved, but only partially (selectivity factor = 1.07), with a mobile phase of hexane/1,2-dichloroethane:95/5 and the stationary phase consisting of the 3,5-dinitrobenzoic acid derivative of (R)-1-naphthylglycine.

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Section: Resultsmentioning

confidence: 99%

The resolution of five racemic α‐lactams by HPLC

Hur

Lengyel

et al. 2007

Chirality

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“…The filtrate was concentrated under vacuum, and the residue was purified by flash chromatography with a 50:50 hexanes/Et 2 O mixture as eluant. b-lactams 19, [19] 20, [20] 21, [20] 22, [21] and 27 [16a] were known compounds.…”

Section: Methods D (Compound 8)mentioning

confidence: 99%

Soluble-Polymer-Supported Synthesis ofβ-Lactams on a Modified Poly(ethylene glycol)

et al. 2000

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A modified poly(ethylene glycol) (PEG) has been developed for the soluble-polymer-supported synthesis of beta-lactams. The monomethylether of PEG (MeOPEG) with an average M(W) of 5000 was used as the support, a 4-(3-propyl)phenyl residue as the spacer, and a 4-oxyphenylamino group as the moiety with the reactive functionality. From this modified PEG representative aromatic, heteroaromatic, unsaturated, and aliphatic imines were obtained in high yields by different procedures. The polymer-supported imines were then employed to prepare several beta-lactams by enolate/imine condensation and ketene/imine cycloaddition. Examples of the control of the absolute stereochemistry during the azetidinone ring formation are also reported. The reactions carried out on the polymer-bound imines showed a remarkable similarity to those performed on nonimmobilized imines, both in terms of yields and stereoselectivities. Removal of the beta-lactams from the polymer has also been accomplished to directly deliver the N-unsubstituted azetidinones.

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“…The enantiomeric purity and configuration of 3-and 4aryl-/3-lactams can be determined by HPLC with modest resolution on amino acid derived stationary phases. Improved resolution can be achieved by converting the /3-lactam (3or 4aryl or alkyl substituents) into N-3,4-dinitrobenzoyl esters via ring opening (83).…”

Section: Amidesmentioning

confidence: 99%