3 research outputs found
UgiāSmiles Couplings of 4-Substituted Pyridine Derivatives: A Fast Access to Chloroquine Analogues
4-Hydroxy and mercapto pyridines were successfully tested in UgiāSmiles couplings. Such multicomponent reactions applied to quinoline derivatives afford a very convenient and short synthesis of antimalarial analogues
Substituent Effects in UgiāSmiles Reactions
In a recent communication, we described
the mechanism of the well-known
Ugi-type reactions with a model system (J. Org. Chem. 2012, 77, 1361ā1366). Herein, focusing on the UgiāSmiles coupling,
we study the effects of each of the four reactants on the energy profile
to further explain the experimental results. The variations observed
with different carbonyl compounds rely on their influence on the formation
of the aryl-imidate, whereas the variations on the amine preferentially
affect the Smiles rearrangement. The effect of substituents on the
phenol derivative is seen upon both aryl-imidate formation and the
rearrangement. The effect of the isocyanide substituents is less pronounced
Challenging 50 Years of Established Views on Ugi Reaction: A Theoretical Approach
The Ugi reaction is one of the most famous multicomponent
couplings,
and its efficiency is still explained by the original mechanism suggested
by Ugi in the 60s. This article aims to present a thorough theoretical
study of this reaction. It describes how the imine is activated and
how the new stereogenic center is formed. Our calculations strongly
suggest alternatives to some commonly accepted features, such as the
reversibility of the intermediate steps, and temper the nature of
the driving force of the reaction