Conformational restriction through Cαi ←→ Cαi cyclization: 1-aminocycloheptane-1-carboxylic acid (Ac7c)

Benedetti, Ettore; Blasio, Benedetto Di; Iacovino, Rosa; Menchise, Valeria; Pedone, Carlo; Bonora, Gian Maria; Ettorre, Alessandro; Graci, Laura; Formaggio, Fernando; Crisma, Marco; Valle, Giovanni; Toniolo, Claudio

doi:10.1039/a701473b

Cited by 28 publications

(32 citation statements)

References 47 publications

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“…The bond distances and angles in the hydantoin moieties are comparable to those observed in the corresponding cycloheptane- [14] and cyclooctanespirohydantoins [15], and in the imidazolidine-2,4-dione (hydantoin) [16]. As expected the heterocyclic ring is affected by a π-conjugation of amide type [16] which is evident from the values of the N-C bond lengths (N1-C2, C2-N3 and N3-C4, Table 2).…”

Section: Molecular Structuresupporting

confidence: 76%

“…The angle between the mean planes of the cycloalkane (C5/C6/C7/C8/C9/C10/C11/C12) and hydantoin (N1/C2/N3/C4/C5) rings is 74.2(2)º, 85.0(2)º and 62.6(2)º for (IA), (IB) and (II); respectively, the values for (II) are comparable with those in non-amino [15] (59.6º) and thio cyclooctanespirohydantoines [18] (61.1º). The value for (IA) is also comparable to the one observed in cycloheptanespirohydantoindione [14] (72.4º) and cycloheptanespirohydantoindithione [18] (72.3º) while this is not the case for the (IB) value which is greater by ~ 12º. The two independent molecules in (I) participate in the hydrogen bonding in quite a different manner (Fig.…”

Section: Molecular Structuresupporting

confidence: 64%

“…Such manner of crystal packing is commonly observed for substituted spirohydatoindiones while the cyclohexane, cycloheptane, and cyclooctane non-amino spirohydantoindithiones show structures where the molecules are hydrogen bonded to build one dimensional chains only. Comparison of experimental structural results for reported compounds and NIVZOH, OCSHYD [14,15] shows that the additional amino group and differences in hydrogen bonding pattern do not modify significantly the geometrical parameters of (I) and (II). In (I) and (II) the activation/deactivation of seizures is controlled by the hydantoin moiety, especially by the (N1) centre and the substituent present in position (N3), while the cycloalkane size influences only the degree of the induced activity.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of a spiro center (C5) explains the longer C5-C4 bond distances in (I) and (II), (1.519(4), 1.518(4) and 1.523(3) Å respectively) in comparison with those in hydantoin (1.460(3) Å). In (I) the cycloheptane ring adopts a twist-chair (TC) (molecule IB) and a distorted chair (C) (molecule IA) conformations [17], while the cycloheptane ring in both non-amino cycloheptanespirohydantoindione [14] and cycloheptanespirohydantoindithione [18] derivatives adopts only a TC conformation. The cyclooctane ring in (II) adopts a boat-chair (BC) conformation [19] which is consistent with observed conformations in cyclooctanespirohydantoin [15] and cyclooctanespirohydantoindithione [18].…”

Section: Molecular Structurementioning

confidence: 99%

“…In all reported cycloheptanespiro-5-hydantoins [14,18] the preferred conformation for the cycloheptane moiety is TC. The DFT calculations showed that the C conformer is slightly less stable than the TC conformer by 1.48 kcal mol -1 .…”

Section: Dft Calculationsmentioning

confidence: 99%

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Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

Todorov

Petrova²,

Naydenova

et al. 2009

Open Chemistry

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The crystal structures of 3-amino-cycloheptanespiro-4′-imidazolidine-2′,5′-dione (I) {systematic name: 3-amino-1,3-diazaspiro[4.6] undecane-2,4-dione} and 3-amino-cyclooctanespiro-4′-imidazolidine-2′,5′-dione (II) {systematic name: 3-amino-1,3-diazaspiro[4.7] dodecane-2,4-dione}, have been determined. In both compounds the polar hydantoin groups cause molecules to aggregate via N-H...O and N-H...N interactions, forming a layer structure, in which the cycloalkane rings project outwards from the central, more polar, region. The observed molecular structure is compared with that calculated by density functional theory methods.

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Section: Molecular Structuresupporting

confidence: 76%

Section: Molecular Structuresupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Molecular Structurementioning

confidence: 99%

Section: Dft Calculationsmentioning

confidence: 99%

See 3 more Smart Citations

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

Todorov

Petrova²,

Naydenova

et al. 2009

Open Chemistry

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Comparison of helix-stabilizing effects of α,α-dialkyl glycines with linear and cycloalkyl side chains

et al. 2000

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Comparison of helix-stabilizing effects of α,α-dialkyl glycines with linear and cycloalkyl side chains

Vijayalakshmi¹,

Rao²,

Karle³

et al. 2000

Biopolymers

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The ability of alpha, alpha-di-n-alkyl glycines with linear and cyclic alkyl side chains to stabilize helical conformations has been compared using a model heptapeptide sequence. The conformations of five synthetic heptapeptides (Boc-Val-Ala-Leu-Xxx-Val-Ala-Leu-OMe, Xxx = Ac8c, Ac7c, Aib, Dpg, and Deg, where Ac8c = 1-aminocyclooctane-1-carboxylic acid, Ac7c = 1-aminocycloheptane-1-carboxylic acid, Aib = alpha-aminoisobutyric acid, Dpg = alpha,alpha-di-n-propyl glycine, Deg = alpha,alpha-di-n-ethyl glycine) have been investigated. In crystals, helical conformations have been demonstrated by x-ray crystallography for the peptides, R-Val-Ala-Leu-Dpg-Val-Ala-Leu-OMe, (R = Boc and acetyl). Solution conformations of the five peptides have been studied by 1H-nmr. In the apolar solvent CDCl3, all five peptides favor helical conformations in which the NH groups of residues 3-7 are shielded from the solvent. Successive NiH<-->Ni + 1H nuclear Overhauser effects over the length of the sequence support a major population of continuous helical conformations. Solvent titration experiments in mixtures of CDCl3/DMSO provide evidence for solvent-dependent conformational transitions that are more pronounced for the Deg and Dpg peptides. Solvent-dependent chemical shift variations and temperature coefficients in DMSO suggest that the conformational distributions in the Deg/Dpg peptides are distinctly different from the Aib/Acnc peptides in a strongly solvating medium. Nuclear Overhauser effects provide additional evidence for the population of extended backbone conformations in the Dpg peptide, while a significant residual population of helical conformations is still detectable in the isomeric Ac7c peptide in DMSO.

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Conformational restriction through Cαi ←→ Cαi cyclization: 1-aminocycloheptane-1-carboxylic acid (Ac7c)

Cited by 28 publications

References 47 publications

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

Comparison of helix-stabilizing effects of α,α-dialkyl glycines with linear and cycloalkyl side chains

Comparison of helix-stabilizing effects of α,α-dialkyl glycines with linear and cycloalkyl side chains

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