Abstract
This article describes the palladium-catalysed three-component coupling of 1,3-dicarbonyl
compounds with nucleophiles and propargylic electrophiles for the generation of quaternary
all-carbon centres in a single step, which necessitates the simultaneous control of
regio-, chemo- and enantioselectivity. The use of propargyl enol carbonates, the source
of two of the components, was found to be essential in maintaining high levels of
regiocontrol and chemoselectivity, whereas a careful analysis of pK
a trends of O-, C- and N-nucleophiles as the other coupling partner indicates that
the highest levels of selectivity are likely to be obtained with relatively acidic
species, such as phenols, 1,3-dicarbonyl compounds and aromatic N-heterocycles. Finally,
studies towards the development of the catalytic enantioselective construction of
quaternary all-carbon centres by means of alkenylation and allylic alkylation are
disclosed.
Key words palladium - enantioselective catalysis - quaternary centres - propargylic electrophiles
- 1,3-dicarbonyl compounds
