Crystal structures of Mosher's salt and ester elucidated by X-ray crystallography

Ichikawa, Akio; Ono, Hiroshi; Mikata, Yuji

doi:10.1039/c3ce41160e

Cited by 3 publications

(12 citation statements)

References 52 publications

(115 reference statements)

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“…That is, the carbonyl group was close to the phenyl group. This phenomenon was also observed for the MTPA esters and MTPA salt; we observed the short contacts between the two oxygen atoms and the ortho-hydrogen atoms of phenyl group in the MTPA anion [9]. [28] in which the intramolecular aromatic C-H···π interactions and N-H···O hydrogen bond were observed.…”

Section: Dihedral Angles Of Amide Carbonyl Group and Trifluoromethyl mentioning

confidence: 48%

“…Three covalent bonds separate the two chiral centers C1′ and C2; therefore, L 3 -C1′-L 2 moiety is more flat in this projection. The MTPA ester exhibited the equivalent conformation with substitution of NH for O [9].…”

Section: Introductionmentioning

confidence: 99%

“…However, statistical analyses of the crystal structures elucidated the relative stability of each conformer [25]. Therefore, we reported statistical analyses of the crystal structures of MTPA esters [9].…”

Section: Introductionmentioning

confidence: 99%

“…The resolving ability of 2 is superior to that of 1 in normal phase HPLC. The diastereomeric MαNP esters also exhibit large chemical shift differences (Δδ values) in In 2013, we elucidated the crystal structure of Mosher's salt prepared from (R)-1 and (R)-1-phenylethylamine using X-ray crystallography [9]; Mosher et al prepared this compound via the enantioresolution of rac-1 in ethanol as a less soluble salt [2]. In the course of this study, we found that a number of crystal structures of MTPA amides and MTPA esters were deposited in the CSD.…”

Section: Introductionmentioning

confidence: 99%

“…The properties of the major conformation of the crystalline MTPA ester are as follows [9]: (1) the ester carbonyl group is synperiplanar (sp, dihedral angle 0° to ±30°) [26] to the trifluoromethyl group; (2) the trifluoromethyl group is in the staggered conformation; (3) the methine group of the alcohol moiety is syn to the carbonyl group; (4) the phenyl plane is inclined from the O-Cchiral bond of the methoxy moiety; (5) the methyl group of the methoxy moiety is antiperiplanar (ap, dihedral angle ±150° to 180°) [26] to the ipso-carbon atom of the phenyl group. Thus, our database study proposed a modified conformational model of the MTPA ester.…”

Section: Introductionmentioning

confidence: 99%

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Characteristic Conformation of Mosher’s Amide Elucidated Using the Cambridge Structural Database

2015

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Abstract:Conformations of the crystalline 3,3,3-trifluoro-2-methoxy-2-phenylpropanamide derivatives (MTPA amides) deposited in the Cambridge Structural Database (CSD) were examined statistically as Racid-enantiomers. The majority of dihedral angles (48/58, ca. 83%) of the amide carbonyl groups and the trifluoromethyl groups ranged from -30° to 0° with an average angle θ 1 of −13°. The other conformational properties were also clarified: (1) one of the fluorine atoms was antiperiplanar (ap) to the amide carbonyl group, forming a staggered conformation; (2) the MTPA amides prepared from primary amines showed a Z form in amide moieties; (3) in the case of the MTPA amide prepared from a primary amine possessing secondary alkyl groups (i.e., Mosher-type MTPA amide), the dihedral angles between the methine groups and the carbonyl groups were syn and indicative of a moderate conformational flexibility; (4) the phenyl plane was inclined from the O-Cchiral bond of the methoxy moiety with an average dihedral angle θ 2 of +21°; (5) the methyl group of the methoxy moiety was ap to the ipso-carbon atom of the phenyl group.

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Section: Dihedral Angles Of Amide Carbonyl Group and Trifluoromethyl mentioning

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristic Conformation of Mosher’s Amide Elucidated Using the Cambridge Structural Database

2015

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Nonsteroidal Anti-Inflammatory Drugs–1-Phenylethylamine Diastereomeric Salts: A Systematic Solid-State Investigation

Rossi

Ceccarelli

Milazzo

et al. 2021

Crystal Growth & Design

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The solid-state investigation of the diastereomeric salts (S)-ibuprofen (S-Ibu), (S)-naproxen, (S-Nap), and (S)-ketoprofen (S-Ket) with (R)-(+)- and (S)-(−)-1-phenylethylamine, R-PEA, and S-PEA respectively, has been carried out by using a combination of experimental and in-silico tools. The focus was on their crystal packing and on the stability/transformation of their solid forms under different experimental conditions with the final aim of extracting useful information on the forces/features which could be exploited for the chiral separation of the corresponding racemic compounds. All the salts are 21-column crystals, each column consisting of API and 1-phenylethylamine ions assembled via the 1-phenylethylammonium-carboxylate supramolecular heterosynthon which originates a R 4 3 (10) pattern, the intercolumns contacts being definitely weaker. In spite of an overall similarity in the crystal packing forces and motifs of the anhydrous salts, the temperature stability range suggests that the homochiral species are the most stable. The fact that the homochiral salt of S-Ket (S-Ket_S-PEA) is stable toward the hydration, at variance with the heterochiral one (S-Ket_R-PEA), further confirms this hypothesis. On the other hand, preliminary sorption tests show that S-Ket and S-Ibu preferentially capture the homochiral PEA (S-Nap is not selective). This behavior has been correlated to the almost planar boundary surfaces which characterize and differentiate the 21 sheets in S-Ket_S-PEA and S-Ibu_S-PEA salts with respect to the corresponding heterochiral ones.

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The Crystal Structure of the More-soluble Mosher’s Salt

2017

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Crystal structures of Mosher's salt and ester elucidated by X-ray crystallography

Cited by 3 publications

References 52 publications

Characteristic Conformation of Mosher’s Amide Elucidated Using the Cambridge Structural Database

Characteristic Conformation of Mosher’s Amide Elucidated Using the Cambridge Structural Database

Nonsteroidal Anti-Inflammatory Drugs–1-Phenylethylamine Diastereomeric Salts: A Systematic Solid-State Investigation

The Crystal Structure of the More-soluble Mosher’s Salt

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