Substituted (E)‑2-Oxo-3-butenoates: Reagents for Every Enantioselectively-Catalyzed Reaction

α,β-Unsaturated carbonyl derivatives are suitable substrates for
several reactions involving the entire CCCO fragment,
the carbonyl group, or the double bond. Among them, 4-
substituted (E)-2-oxo-3-butenoates (1) have a specific advantage
due to the presence of a further carboxylic group attached
to the carbonyl carbon atom because the resulting 1,2-
dicarbonyl system may be coordinated to a Lewis acid. This
coordination increases the reactivity of the substrate, and use of
an asymmetric catalyst may induce enantioselectivity in the
reactions.
In view of the importance of these molecules in the synthesis
of organic compounds, arylidene pyruvates (1, R = Ar) have
been considered as worthy of a general review, starting with
their syntheses, the chemical properties, and the various
reactivity.