A Highly Stereoselective Diels–Alder Cycloaddition of Enones with Chiral Cyclic 2‑Amidodienes Derived from Allenamides

Abstract

Lewis acid promoted Diels–Alder cycloadditions of a series of <i>de novo</i> chiral cyclic 2-amidodienes are described. These cyclic 2-amidodienes are derived from chiral α-allyl allenamides via a sequence of <i>E-</i>selective 1,3-H shift and 6π-electron pericyclic ring closure. With enones serving as effective dienophiles, these cycloadditions can be highly diastereoselective depending upon the chiral amide substituent, thereby representing a facile entry to optically enriched [2.2.2]bicyclic manifolds