The Asymmetric Diels–Alder Reaction of α,β-Unsaturated Aldehydes with Dienes Using a Chiral Boron Reagent as a Catalyst

Abstract
The asymmetric Diels–Alder reaction of α,β-unsaturated aldehydes with cyclopentadiene is catalyzed by a novel chiral boron reagent generated in situ from boron tribromide and a chiral prolinol derivative, to afford the corresponding adducts in good yields with fairly good to excellent ees.