Novel Cerium(III)–(R)-BNP Complex as a Storable Chiral Lewis Acid Catalyst for the Enantioselective Hetero-Diels–Alder Reaction

A novel Ce(III)–(R)-BNP complex was conveniently prepared from CAN and (R)-BNP–Na, then successfully used as a homogeneous catalyst for the asymmetric hetero-Diels–Alder reaction affording, after acidic work-up, 6-substituted 5,6-dihydro-4H-pyran-4-one derivatives with high enantioselectivities (up to 94% ee). A mechanistically interesting positive nonlinear effect was also observed.