Simultaneous determination of enantiomeric purity and erythro/threo relationship in chiral 1,2-aminoalcohols by NMR using (R)-(+)-t-butylphenylphosphinothioic acid

Gunderson, Karl; Shapiro, Michael J.; Doti, Robert A.; Skiles, Jerry W.

doi:10.1016/s0957-4166(99)00327-4

Cited by 21 publications

(13 citation statements)

References 6 publications

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“…41 Prior to this work, there was reportedly no convenient method for directly determining the enantiomeric composition of halohydrins. 43 One of the most challenging problems in chiral discrimination involves compounds in which the site of chirality is remote from the site at which the CDA binds. 42 The reagent is based on a C 3 chiral phosphorus species prepared with an ␣-phenylethylamino trisaminoamine ligand (11).…”

Section: Chiral Reagents For Determining Ee and Acmentioning

confidence: 99%

Chiral reagents for the determination of enantiomeric excess and absolute configuration using NMR spectroscopy

2003

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Section: Chiral Reagents For Determining Ee and Acmentioning

confidence: 99%

Chiral reagents for the determination of enantiomeric excess and absolute configuration using NMR spectroscopy

2003

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“…Discrimination was noted in the 1 H NMR spectrum and assignment of the erythro and threo conformers could be made on the basis of differences in the coupling constants. 43 One of the most challenging problems in chiral discrimination involves compounds in which the site of chirality is remote from the site at which the CDA binds. A system that contains a 31 P phosphite probe embedded in a large chiral, helicine (13, Fig.…”

Section: Chiral Reagents For Determining Ee and Acmentioning

confidence: 99%

Chiral Reagents for the Determination of Enantiomeric Excess and Absolute Configuration Using NMR Spectroscopy

Wenzel

Wilcox

2003

ChemInform

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Recent advances in the development of chiral derivatizing and solvating agents that facilitate the determination of enantiomeric excess and absolute configuration are reviewed. These include metal-containing species, host-guest systems, donoracceptor compounds, and liquid crystal discriminating agents. In the aggregate, these reagents can be used to analyze a wide range of compound classes. Chirality 15: 256-270, 2003.

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“…The solvent was the removed from the filtrate to yield a clear oil which was placed under vacuum where it solidified, (5.91 g, 98%); mp 53-56 °C (Lit. 16 18 gave an ee of >99%.…”

Section: Potassium (2s3s)-3-phenyloxirane-2-carboxylate (19)mentioning

confidence: 99%

Synthesis of Single-Enantiomer 6-Hydroxy-7-phenyl-1,4-oxazepan-5-ones

Becker¹,

Dembofsky²,

Hall³

et al. 2005

Synthesis

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An efficient two-step preparation of (6R,7R)-6-hydroxy-7-phenyl-1,4-oxazepan-5-ones (1) starting from aminoethanols and (2R,3S)-3-phenyloxirane-2-carboxylic ethyl ester or potassium salt has been described. The most efficient catalyst identified for the ring closure of the resulting intermediate epoxyamides was Sc(OTf) 3 . By choice of appropriate chiral starting substituted aminoethanol and 3-phenyloxirane-2-carboxylic derivatives, the procedure allows facile synthesis of other single enantiomer 6-hydroxy-7-phenyl-1,4-oxazepan-5-ones.We wished to develop a synthesis of (6R,7R)-6-hydroxy-7-phenyl-1,4-oxazepan-5-one (1) (Figure 1) that would allow facile access for mono-, di-and tri-substitution at R 1 , R 2 , R 3 , R 4 and R 5 . Figure 1 6-Hydroxy-7-phenyl-1,4-oxazepan-5-one diastereomers 1-4. See Table 2 for the letter assignment of R 1 -R 5 combinations prepared in this paper.A report 1 on the cyclization of the racemic cis-epoxide (5, cis-racemate, Scheme 1) with MgI 2 to yield racemic trans-2-phenyltetrahydrofuran-3-ol (7, trans-racemate) led us to speculate whether a similar transformation would be possible with epoxyamide 8. We anticipated that as with 5 and other similar alcohols, esters, and aldehydes, 2 the epoxyamide 8 would exhibit chelation-controlled epoxide opening with MgI 2 to yield the iodohydrin 9. A 7-exo-tet displacement of the iodide would theoretically control the oxazepine versus pyran issue.In order to rapidly test this approach we examined the reaction of N-(2-hydroxy-2-phenylethyl)-N-methyl-3-phenyloxirane-2-carboxamide (11df, Scheme 2) with MgI 2 under the conditions employed by Karikomi. 1 A 43% yield of a 1:1 mixture of the 6-hydroxy-4-methyl-2,7-diphenyl-1,4-oxazepan-5-ones 1f and 2d was obtained. The relative stereochemistry of the substituents of the product was determined by a NMR NOE study. The material used in the study was prepared in 46% yield by the method of Huang 3 from commercial ethyl phenylglycidate (90% trans by 1 H NMR) and DL-a-(methylaminomethyl)benzylalcohol. NMR spectral analysis of 11df confirmed that the material consisted only of trans-epoxyamide. We did not further examine the diastereomeric balance of 11df. Diastereomeric enrichment in the preparation of 11df would compromise a rigorous mechanistic Scheme 2 Reagents and conditions: a) Ethyl 3-phenyloxirane-2-carboxylate, MeOH, cat. NaOMe, -20 °C; b) 10 mol% MgI 2 , refluxing THF. Scheme 1Downloaded by: Florida State University Libraries. Copyrighted material.

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Simultaneous determination of enantiomeric purity and erythro/threo relationship in chiral 1,2-aminoalcohols by NMR using (R)-(+)-t-butylphenylphosphinothioic acid

Cited by 21 publications

References 6 publications

Chiral reagents for the determination of enantiomeric excess and absolute configuration using NMR spectroscopy

Chiral reagents for the determination of enantiomeric excess and absolute configuration using NMR spectroscopy

Chiral Reagents for the Determination of Enantiomeric Excess and Absolute Configuration Using NMR Spectroscopy

Synthesis of Single-Enantiomer 6-Hydroxy-7-phenyl-1,4-oxazepan-5-ones

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