Asymmetric Allylation of Furfural Derivatives: Synergistic Effect of Chiral Ligand and Organocatalyst on Stereochemical Control

An
asymmetric allylation reaction at the benzylic position of furfurals
that are easily accessed from 5-HMF, which is a biomass derivative,
has been established by palladium and amine cooperative catalysis.
The high levels of enantioselectivity of up to 97% enantiometric excess
(ee) were enabled by the synergistic stereochemical control of a chiral
TADDOL-based phosphoramidite ligand and a chiral diphenylprolinol
silyl ether. The product could be feasibly transformed to chiral aryl-substituted
spiroacetal via a four-step reaction sequence.