scholarly journals Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

2022 ◽  
Vol 18 ◽  
pp. 102-109
Author(s):  
Jolita Bruzgulienė ◽  
Greta Račkauskienė ◽  
Aurimas Bieliauskas ◽  
Vaida Milišiūnaitė ◽  
Miglė Dagilienė ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Diffraction Data ◽  
Hplc Analysis ◽  
Hydroxylamine Hydrochloride ◽  
Building Blocks ◽  
Chiral Hplc ◽  
Efficient Synthesis ◽  
X Ray Diffraction ◽  
X Ray

A convenient and efficient synthesis of novel achiral and chiral heterocyclic amino acid-like building blocks was developed. Regioisomeric methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates were prepared by the reaction of β-enamino ketoesters (including azetidine, pyrrolidine or piperidine enamines) with hydroxylamine hydrochloride. Unambiguous structural assignments were based on chiral HPLC analysis, 1H, 13C, and 15N NMR spectroscopy, HRMS, and single-crystal X-ray diffraction data.

Axially Chiral Bis(α-amino Acid)s and Their Deamino Analogues. Synthesis and Configurational Assignment

1998 ◽  
Vol 63 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Miloš Tichý ◽  
Luděk Ridvan ◽  
Miloš Buděšínský ◽  
Jiří Závada ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nmr Spectra ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
X Ray ◽  
Configurational Assignment ◽  
Symmetry Properties ◽  
Axially Chiral ◽  
Polymeric Structures

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.

Preparation and Crystal Structures of the Isotypic Compounds CdXO4 · 2 HgO (X = S, Se)

2004 ◽  
Vol 59 (3) ◽  
pp. 281-285 ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Single Crystals ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Building Blocks ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Space Group ◽  
X Ray ◽  
Structure Factors

Colourless single crystals of the compounds CdXO4 · 2 HgO (X = S, Se) were obtained under hydrothermal conditions (250 °C, 5 d), starting from stoichiometric amounts of HgO, CdSO4 ·7H2O and CdSeO4 ·2H2O, respectively. The crystal structures were determined from X-ray diffraction data sets. The CdXO4 · 2HgO compounds crystallise isotypically with two formula units in space group P1̅ (# 2) [CdSO4 · 2HgO (CdSeO4 · 2HgO): a = 6.793(2) (6.9097(5)) Å , b = 7.205(2) (7.1786(6)) Å , c=7.359(2) (7.4556(6)) Å ,α =73.224(6) (74.586(2))°, β =66.505(6) (68.229(1))°, γ =63.054(5) (63.886(1))°, 1670 (1786) structure factors, 92 parameters, R[F2 > 2σ(F2)] = 0.0379 (0.0244)] and are made up from zig-zag [O-Hg-O]∞ chains with very short bonds of d̅(Hg-O) 2.025 Å , distorted [CdO6] octahedra (d̅(Cd-O)= 2.297 Å ), and XO4 tetrahedra (d̅(S-O)= 1.458 Å , d̅(Se-O)= 1.633 Å ) as the main building blocks. The CdXO4 ·2HgO compounds reveal no structural relationship with the corresponding HgXO4 ·2HgO phases

Symmetry breaking in the solid state of 9,10-anthracene amino acid conjugates as seen by X-ray diffraction and NMR spectroscopy

2020 ◽  
Vol 1221 ◽  
pp. 128834
Author(s):  
Berislav Perić ◽  
Gábor Szalontai ◽  
Mladen Borovina ◽  
Dražen Vikić-Topić ◽  
Srećko I. Kirin
Keyword(s):  
Amino Acid ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Symmetry Breaking ◽  
X Ray Diffraction ◽  
Amino Acid Conjugates ◽  
X Ray

scholarly journals Hemi-Synthesis of Chiral Imine, Benzimidazole and Benzodiazepines from Essential Oil of Ammodaucus leucotrichus subsp. leucotrichus

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 975 ◽  
Author(s):  
Farid Chebrouk ◽  
Khodir Madani ◽  
Brahim Cherfaoui ◽  
Leila Boukenna ◽  
Mónica Válega ◽  
...  
Keyword(s):  
Essential Oil ◽  
Hplc Analysis ◽  
Reaction Medium ◽  
2D Nmr ◽  
Chiral Hplc ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reaction Proceeds ◽  
Derivatives Of

The hemi-synthesis of chiral imine, benzimidazole and benzodiazepine structures is reported by the condensation of (S)-(−)-perillaldehyde, the major phytochemical of Ammodaucus leucotrichus subsp. leucotrichus essential oil, with different amine derivatives of 2,3-diaminomaleonitrile, o-phenylenediamine and 3-[(2-aminoaryl)amino]dimedone. The reaction proceeds in situ at ambient temperature without prior isolation of the natural (S)-(−)-perillaldehyde. Final products precipitate in the ethanolic reaction medium. 2D NMR and single-crystal X-ray diffraction studies were used to unequivocally characterize the structures in solution and in the solid state, respectively. Chiral HPLC analysis confirms the formation of unique enantiomers and diastereomeric mixtures.

scholarly journals X-ray powder diffraction analysis of a new palladium(II) amino acid complex

2004 ◽  
Vol 19 (3) ◽  
pp. 270-271 ◽  
Author(s):  
Pedro P. Corbi ◽  
Antonio C. Massabni ◽  
Claudio M. Costa-Neto
Keyword(s):  
Amino Acid ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Acid Complex ◽  
X Ray ◽  
Cell Parameters ◽  
Amino Acid Complex ◽  
Orthorhombic Cell

Powder X-ray diffraction data for a new palladium(II) amino acid complex, of composition PdC12H20N2O4S2, are presented in this paper. Orthorhombic cell parameters are: a=10.740 Å, b=19.999 Å, and c=5.2470 Å. © 2004 International Centre for Diffraction Data.

scholarly journals Crystal Structure of the Disordered Non-Centrosymmetric Compound Fe0.43Mo2.56SbO9.5

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 40
Author(s):  
Sk Ali ◽  
Sven Lidin ◽  
Mats Johnsson
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Lone Electron Pair ◽  
Electron Pair ◽  
Building Blocks ◽  
Fold Axis ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Single crystals of Fe0.43Mo2.56SbO9.5 were obtained by hydrothermal techniques at 230 °C. The crystal structure was determined from single crystal X-ray diffraction data. The compound crystallizes in the non-centrosymmetric space group Pc with unit cell parameters a = 4.0003(2) Å, b = 7.3355(3) Å, c = 12.6985(6) Å, β = 90°. The crystal structure comprises five crystallographically independent M atoms and one Sb3+ atom, M atoms are of two kinds of partially occupied sites Mo6+ and Fe3+. The building blocks consist of [SbO3O0.5O0.5E] octahedra (E = lone electron pair) and [(Mo/Fe)O6] octahedra. The M = (Mo, Fe) and O atoms are arranged in a distorted hexagonal 2D-net, not the Sb atoms. The distortion of the net and consequently the symmetry reduction results mainly from the location of the Sb atoms. Disorder manifests itself as a splitting of the metal sites and as a consequent shortening of the Mo–Fe distances. Six (Mo/Fe)O6 octahedra are connected to form a pseudohexagonal channel. The Sb3+ atom is displaced from the pseudo-six-fold axis.

scholarly journals Structural properties of methoxy derivatives of benzyl bromide, determined from powder X-ray diffraction data

2005 ◽  
Vol 20 (4) ◽  
pp. 345-352 ◽  
Author(s):  
Zhigang Pan ◽  
Eugene Y. Cheung ◽  
Kenneth D. M. Harris ◽  
Edwin C. Constable ◽  
Catherine E. Housecroft
Keyword(s):  
Structural Properties ◽  
Diffraction Data ◽  
Benzyl Bromide ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Solution ◽  
Derivatives Of ◽  
Potential Use

Structure determination of 3,5-dimethoxybenzyl bromide and 3,4,5-trimethoxybenzyl bromide has been carried out from laboratory powder X-ray diffraction data using the direct-space Genetic Algorithm technique for structure solution followed by Rietveld refinement. These two compounds are of interest for their potential use as building blocks for the synthesis of dendritic materials. Although the two molecules differ only in the presence/absence of the methoxy group at the 4-position of the aromatic ring, the structural properties of the two materials are significantly different.

C−H⋅⋅⋅O Hydrogen Bond Mediated Chain Reversal in a Peptide Containing aγ-Amino Acid Residue, Determined Directly from Powder X-ray Diffraction Data

2002 ◽  
Vol 114 (3) ◽  
pp. 512-514 ◽  
Author(s):  
Eugene Y. Cheung ◽  
Emma E. McCabe ◽  
Kenneth D. M. Harris ◽  
Roy L. Johnston ◽  
Emilio Tedesco ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Amino Acid ◽  
Amino Acid Residue ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chain Reversal

scholarly journals X-ray powder diffraction analysis of methionine sulfoxide

2001 ◽  
Vol 16 (3) ◽  
pp. 163-164
Author(s):  
Pedro P. Corbi ◽  
Petr Melnikov ◽  
Antonio C. Massabni
Keyword(s):  
Amino Acid ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Methionine Sulfoxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Monoclinic Cell

Powder X-ray diffraction data for methionine sulfoxide, C5H11NO3S, obtained from the commercial amino acid, are presented in this work. Monoclinic cell parameters are: a=15.500 Å; b=3.820 Å; c=13.490 Å; β=97.300 °.

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