Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State

Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State

The conformation of the title compounds was determined in solution by <sup>1</sup>H-NMR spectroscopy and in solid state by single-crystal X-ray diffraction (XRD) complemented with density functional theory. The compounds were found to exist exclusively in solution and solid state as <...

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Main Authors: Malose J. Mphahlele, Marole M. Maluleka, Richard M. Mampa
Format: Article
Language:English
Published: MDPI AG 2019-05-01
Series:Crystals
Subjects:
<i>trans-</i>2-amino-3,5-dibromochalcone epoxides
NMR spectroscopy
XRD
DFT
3-arylquinolin-4(1<i>H</i>)-ones
Online Access:https://www.mdpi.com/2073-4352/9/6/277
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spelling doaj-40f0251b10df4d96ba99574ad96102022020-11-25T01:12:18ZengMDPI AGCrystals2073-43522019-05-019627710.3390/cryst9060277cryst9060277Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid StateMalose J. Mphahlele0Marole M. Maluleka1Richard M. Mampa2Department of Chemistry, College of Science, Engineering and Technology, University of South Africa, Private Bag X06, Florida 1710, South AfricaDepartment of Chemistry, College of Science, Engineering and Technology, University of South Africa, Private Bag X06, Florida 1710, South AfricaDepartment of Chemistry, University of Limpopo, Private Bag X1106, Sovenga 0727, South AfricaThe conformation of the title compounds was determined in solution by <sup>1</sup>H-NMR spectroscopy and in solid state by single-crystal X-ray diffraction (XRD) complemented with density functional theory. The compounds were found to exist exclusively in solution and solid state as <i>trans</i>-2-aminochalcone epoxides with strong intramolecular hydrogen bonding interaction between the amino and carbonyl groups. These 2-aminochalcone epoxides experienced a solvent effect in DMSO-<i>d</i><sub>6</sub>, which resulted in an anomalous chemical shift for the &#945;-hydrogen signal, presumably due to complexation of solute molecules with DMSO. The solute&#8722;solvent interaction would probably fix the <i>trans</i> conformation of epoxyketone such that &#945;-H is more accessible to both aryl rings, and in turn, experience their combined anisotropic effect. Intermolecular interactions in the crystal structures were confirmed and quantified using the Hirshfeld surface analysis. Moreover, the <i>trans</i> stereochemistry of the &#945;-epoxyketones facilitated direct one-pot sequential sulfuric acid-mediated ring opening and aryl migration to afford the corresponding 3-arylquinolin-4(1<i>H</i>)-ones (azaisoflavones).https://www.mdpi.com/2073-4352/9/6/277<i>trans-</i>2-amino-3,5-dibromochalcone epoxidesNMR spectroscopyXRDDFT3-arylquinolin-4(1<i>H</i>)-ones
collection DOAJ
language English
format Article
sources DOAJ
author Malose J. Mphahlele
Marole M. Maluleka
Richard M. Mampa
spellingShingle Malose J. Mphahlele
Marole M. Maluleka
Richard M. Mampa
Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
Crystals
<i>trans-</i>2-amino-3,5-dibromochalcone epoxides
NMR spectroscopy
XRD
DFT
3-arylquinolin-4(1<i>H</i>)-ones
author_facet Malose J. Mphahlele
Marole M. Maluleka
Richard M. Mampa
author_sort Malose J. Mphahlele
title Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
title_short Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
title_full Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
title_fullStr Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
title_full_unstemmed Elucidation of the Structure of the 2-amino-3,5-Dibromochalcone Epoxides in Solution and Solid State
title_sort elucidation of the structure of the 2-amino-3,5-dibromochalcone epoxides in solution and solid state
publisher MDPI AG
series Crystals
issn 2073-4352
publishDate 2019-05-01
description The conformation of the title compounds was determined in solution by <sup>1</sup>H-NMR spectroscopy and in solid state by single-crystal X-ray diffraction (XRD) complemented with density functional theory. The compounds were found to exist exclusively in solution and solid state as <i>trans</i>-2-aminochalcone epoxides with strong intramolecular hydrogen bonding interaction between the amino and carbonyl groups. These 2-aminochalcone epoxides experienced a solvent effect in DMSO-<i>d</i><sub>6</sub>, which resulted in an anomalous chemical shift for the &#945;-hydrogen signal, presumably due to complexation of solute molecules with DMSO. The solute&#8722;solvent interaction would probably fix the <i>trans</i> conformation of epoxyketone such that &#945;-H is more accessible to both aryl rings, and in turn, experience their combined anisotropic effect. Intermolecular interactions in the crystal structures were confirmed and quantified using the Hirshfeld surface analysis. Moreover, the <i>trans</i> stereochemistry of the &#945;-epoxyketones facilitated direct one-pot sequential sulfuric acid-mediated ring opening and aryl migration to afford the corresponding 3-arylquinolin-4(1<i>H</i>)-ones (azaisoflavones).
topic <i>trans-</i>2-amino-3,5-dibromochalcone epoxides
NMR spectroscopy
XRD
DFT
3-arylquinolin-4(1<i>H</i>)-ones
url https://www.mdpi.com/2073-4352/9/6/277
work_keys_str_mv AT malosejmphahlele elucidationofthestructureofthe2amino35dibromochalconeepoxidesinsolutionandsolidstate
AT marolemmaluleka elucidationofthestructureofthe2amino35dibromochalconeepoxidesinsolutionandsolidstate
AT richardmmampa elucidationofthestructureofthe2amino35dibromochalconeepoxidesinsolutionandsolidstate
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