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Theoretical Study of the Regioselectivity of the Interaction of 3-Methyl-4-Pyrimidone and 1-Methyl-2-Pyrimidone with Lewis Acids.
MedLine Citation:
PMID:  22853776     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
A DFT study is performed to determine the stability of the complexes formed between either the N or O site of 3-methyl-4-pyrimidone and 1-methyl-2-pyrimidone molecules and different ligands. The studied ligands are boron and alkali Lewis acids, namely B(CH3)3, HB(CH3)2, H2B(CH3), BH3, H2BF¬¬¬, HBF2, BF3, Li+, Na+ and K+. The acids are divided into two groups according to their hardness. The reactivity predictions, according to the Molecular Electrostatic Potential (MEP) map and the Natural Bond Orbital (NBO) analysis, are in agreement with the calculated relative stabilities. Our findings reveal a strong regioselectivity with borane and its derivatives preferring the nitrogen site in both pyrimidone isomers, while a preference for oxygen is observed for the alkali acids in the 3-methyl-4-pyrimidone molecule. The complexation of 1-methyl-2-pyrimidone with these hard alkali acids does not show any discrimination between the two sites due to the presence of a continuous delocalized density region between the nitrogen and the oxygen atoms. The preference of boron Lewis acids towards the N site is due to the stronger B-N bond as compared to the B-O bond. The influence of fluorine or methyl substitution on the boron atom is discussed through natural orbital analysis (NBO) concentrating on the overlap of the boron empty p-orbital with the F lone pairs and methyl hyperconjugation respectively. The electrophilicity of the boron acids gives a good overall picture of the interaction capabilities with the Lewis base. Keywords: 3-methyl-4-pyrimidone, 1-methyl-2-pyrimidone, DFT, hardness, Molecular Electrostatic Potential, NBO Analysis.
Authors:
Emile Kasende Okuma; Jules Tshishimbi Muya; Lies Broeckaert; Guido Maes; Paul Geerlings
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-1
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  -     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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