Structure and reactivity relationship studies for guanidine-organocatalyzed direct intramolecular aldolization of ketoaldehydes
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Structure-reactivity studies are performed to explore the reaction mechanism of guanidine-catalyzed intramolecular aldol reaction of ketoaldehydes. A large number of guanidines and guanidine-like catalysts were synthesized and their properties were determined. Kinetic profiles and pKa values of the catalysts were measured and correlated to reaction barriers calculated using density functional theory. The calculations show that the structural rigidity determines the pKa of the guanidines. Although the basicity is a very important factor in the catalyst, it is not sufficient to account for the full catalytic power. The availability of two reaction sites aligned for proton shuttling in the transition states is also an essential feature that helps us rationalize the reactivity pattern observed.
IdentifiersURN: urn:nbn:se:kth:diva-11615OAI: oai:DiVA.org:kth-11615DiVA: diva2:278333
QC 201007192009-11-252009-11-252010-07-19Bibliographically approved