Re-Examination of Proline-Catalyzed Intermolecular Aldol Reactions: An Ab Initio Kinetic Modelling Study

The full catalytic cycle of the proline-catalyzed intermolecular aldol reaction of acetone and p-nitrobenzaldehyde in acetone solvent has been investigated by quantum chemistry at the G3(MP2,CC)//M062X/6–31+G(d)/SMD level of theory, and the results used to develop an ab initio kinetic model. Proline...

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Bibliographic Details
Published in:Topics in catalysis 2022-02, Vol.65 (1-4), p.354-365
Main Authors: Yu, Li-Juan, Blyth, Mitchell T., Coote, Michelle L.
Format: Article
Language:English
Subjects:
Acetone
Aldehydes
Bonding
Catalysis
Catalysts
Characterization and Evaluation of Materials
Chemical reactions
Chemistry
Chemistry and Materials Science
Condensates
Conversion
Covalent bonds
Industrial Chemistry/Chemical Engineering
Original Paper
Pharmacy
Physical Chemistry
Proline
Quantum chemistry
Stereochemistry
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Summary:The full catalytic cycle of the proline-catalyzed intermolecular aldol reaction of acetone and p-nitrobenzaldehyde in acetone solvent has been investigated by quantum chemistry at the G3(MP2,CC)//M062X/6–31+G(d)/SMD level of theory, and the results used to develop an ab initio kinetic model. Proline catalyzes the aldol reaction according to the enamine mechanism. The initial reaction between proline and acetone was reinvestigated, and a revised mechanism for enamine formation is proposed in which a second proline assists the process contributing to the enamine formation. Using various initial concentrations of proline while keeping the experimental ratio of water, aldehyde and acetone constant, we find that the enamine formation from the first-order to proline pathway dominates when the concentration of proline is low ( 1.0 M) excess water is expected to decrease %ee. Side reactivity, including aldol condensation, acetone self-aldolization, oxazolidinone formation and azomethine and 1-oxapyrrolizidine formation were
ISSN:1022-5528
1572-9028
DOI:10.1007/s11244-021-01501-5