A Study of the Crystal Structure and Hydrogen Bonding of 3-Trifluoroacetyloxime Substituted 7-Acetamido-2-aryl-5-bromoindoles

The 7-acetyl-2-aryl-5-bromo-3-(trifluoroacetyl)indoles 1a-d were reacted with hydroxylamine hydrochloride (2.2 equiv.) in the presence of pyridine in ethanol under reflux to afford the corresponding diketo oxime derivatives 2a-d. Beckmann rearrangement of the latter with trifluoroacetic acid under r...

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Bibliographic Details
Published in:Crystals (Basel) 2018-07, Vol.8 (7), p.274
Main Author: Mphahlele, Malose
Format: Article
Language:English
Subjects:
7-acetyl-2-aryl-5-bromo-3-(trifluoroacetyl)indoles
Angles (geometry)
Aromatic compounds
Beckmann rearrangement
Biological activity
Cancer
Chromatography
Crystal structure
Crystallization
Crystallography
Cytotoxicity
Density functional theory
DFT
Ethanol
Hydrogen bonding
Hydrogen bonds
Indoles
Mathematical analysis
Molecular structure
NMR
Nuclear magnetic resonance
oximation
Polymerization
Single crystals
Spectrometry
Studies
Substitutes
Unit cell
X ray spectra
X-ray diffraction
XRD
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Summary:The 7-acetyl-2-aryl-5-bromo-3-(trifluoroacetyl)indoles 1a-d were reacted with hydroxylamine hydrochloride (2.2 equiv.) in the presence of pyridine in ethanol under reflux to afford the corresponding diketo oxime derivatives 2a-d. Beckmann rearrangement of the latter with trifluoroacetic acid under reflux afforded the corresponding 7-acetamido-2-aryl-5-bromo-3-(trifluoroacetyloxime)indoles 3a-d. The structures of the prepared compounds were characterized using a combination of NMR (1H & 13C), IR, and mass spectrometric techniques. The molecular structure of the 3-trifluoroacetyloxime substituted 7-acetamido-2-aryl-5-bromoindoles was unambiguously confirmed by the single crystal X-ray diffraction data of 3d. Structural studies of 3d in the solid state by X-ray crystallography provided evidence of hydrogen bonding networks and π-stacking of the indole moiety. Compound 3d was crystallized in the trigonal space group R-3:H with unit cell dimensions a = 25.1614(13), b = 25.1614(13), c = 17.3032(9) Å, α = β = 90°, γ = 120°, V = 9486.9(11) Å3, Z = 6. The density functional theory (DFT) structural parameters (bond lengths, bond angles, and torsion angles) of the optimized geometry calculated using the B3LYP/6-311G basis set were found to compare favourably with those of the X-ray crystal structure.
ISSN:2073-4352
2073-4352
DOI:10.3390/cryst8070274