Resin-Bound Pyrrolidine Catalysts for Enamine-Mediated Reactions

Significance

Tentagel-bound asymmetric pyrrolidine catalysts 1 and 2 are reported for the preparation of optically active chromanones 5. The catalysts mediated the asymmetric tandem aldol-Michael reactions with high enantioselectivity and complete diastereoselectivity. Thus, the reaction of 3 and cycloalkanones (4 and 6) was carried out with 1 in MeOH. The reaction mixture was then heated under microwave irradiation to give 5a-h in 71-90% yield with up to 97% ee (8 examples). The reaction with 2 under similar conditions afforded ent-5b-g and 5h in 77-94% yield with up to 99% ee (7 examples).