Journal :   Asian Journal of Research in Chemistry

Volume No. :   12

Issue No. :  2

Year :  2019

Pages :   103-111

ISSN Print :  0974-4169

ISSN Online :  0974-4150


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Reaction Intermediates for Microwave Irradiation Assisted Synthesis of N-Aryl Enaminoketones and their subsequent conversion to Quinolines: An experimental and DFT Study



Address:   Avijit Banerji1, Rina Saha2, Nivedita Acharjee*3
1Central Ayurveda Research Institute for Drug Development, CN Block, Sector V, Kolkata 700091, West Bengal, India.
2Centre of Advanced Studies on Natural Products including Organic Synthesis, Department of Chemistry, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata- 700009, West Bengal, India.
3Department of Chemistry, Durgapur Government College, Durgapur-713214 West Bengal, India.
*Corresponding Author
DOI No: 10.5958/0974-4150.2019.00023.3

ABSTRACT:
Reactions of acetyl acetone to aromatic amines have been carried out in presence of p-toluenesulphonic acid and molecular sieves by a new microwave irradiation assisted procedure to generate N-aryl enaminoketones. Two stereoisomeric enaminoketones, viz. cis and trans enaminoketones, are formed as intermediates which are characterized by NMR studies.Computations are performed at the DFT/B3LYP/6-311++G(2d,p) level to analyze the course of these reactions. The computed GIAO nuclear magnetic shielding tensors and experimental data are found to be in good agreement to each other in case of both cis and trans enaminoketones. Transition states and intermediates for the generation of cis and trans enaminoketones are successfully located at DFT/B3LYP/6-311++G(2d,p) level of theory and the relative energies are calculated to rationalize the selectivity of the process. Two transition states and one intermediate are located for both cis and trans pathways. The enaminoketones are subsequently converted to quinolines under acid catalysis with 80% sulphuric acid under microwave irradiation in high yields. This method is a significant improvement on the conventional methods for preparation of substituted quinolines from 1,3-diketones, particularly in view of very short times taken, the cleanness of the reactions and high yields. The present theoretical study of the reaction course at DFT/B3LYP/6-311++G(2d,p) level is the first contribution to computational calculations of such reactions.
KEYWORDS:
Enaminoketones, Quinolines, Microwave Irradiation, DFT, Transition state.
Cite:
Avijit Banerji, Rina Saha, Nivedita Acharjee. Reaction Intermediates for Microwave Irradiation Assisted Synthesis of N-Aryl Enaminoketones and their subsequent conversion to Quinolines An experimental and DFT Study. Asian J. Research Chem. 2019; 12(2):103-111.
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