DFT Studies on the Stereoselective Three-Component Ugi Reaction

Mechanism and stereochemistry of three component Ugi reaction (3C-Ugi) were studied theoretically based on DFT calculations. Structures of reagents, products, intermediates, and transition states were optimized at M062X/631+g(d,p) level of theory in gas phase and in methanol as a common solvent for...

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Published inOrbital : The Electronic Journal of Chemistry Vol. 11; no. 1; pp. 18 - 24
Main Authors Sharifzadeh, Elaheh Sadat, Shiraz, Nader Zabarjad
Format Journal Article
LanguageEnglish
Published Universidade Federal de Mato Grosso do Sul 01.01.2019
Subjects
dft calculation
Methanol
multicomponent reaction
Reagents
stereoselectivity
three-component ugi reactionnent ugi reaction
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Summary:Mechanism and stereochemistry of three component Ugi reaction (3C-Ugi) were studied theoretically based on DFT calculations. Structures of reagents, products, intermediates, and transition states were optimized at M062X/631+g(d,p) level of theory in gas phase and in methanol as a common solvent for this reaction. The reaction takes place through several processes, including atom inversion, bond rotation, acid-base, nucleophile-electrophile competitions. These diverse phenomena were studied to provide a clearer picture of the mechanism of this valuable reaction, especially in terms of stereochemistry considerations. According to the results, the enthalpy of the reaction was -45.9 and -41.2 kcal/mol for the dominant product in gas phase and in methanol. The stereoselectivity of the reaction was under the kinetic control of nucleophilic attack of isocyanide to less hindered si-face ([E.sub.a]= 4.1 compared to 7.4 kcal/mol for re-face) of more stable chiral (E)-iminium in methanol. Keywords: DFT calculation; multicomponent reaction; stereoselectivity; three-component Ugi reaction
ISSN:1984-6428
1984-6428
DOI:10.17807/orbital.v11i1.1214