N-Alkenoylimidazolidin-2-ones as chiral dienophiles in Diels-Alder cycloaddition reactions

Homochiral N-enoylimidazolidin-2-ones 5-8 are readily accessible. practical , and highly diastereoselective dienophiles in dialkylaluminium-promoted Di els-Alder reactions. Acrylate, methacrylate, and (E)-crotonate derivatives bearing ephedrine-based imidazolidin-2-one auxiliaries 1 and 2 undergo rapi d. face-selective cycloadditions under mild conditions. High yields of dias tereomerically homogeneous products 11-14 are readily obtained by crystalli sation or chromatography. The reactivity scope of these systems is extended to less reactive dienes through auxiliary tuning by the application of alt ernative asparagine-based imidazolidin-2-one auxiliaries 3 and 4.