Asymmetric Diels‐Alder Reactions of Cyclopentadiene with N‐Crotonoyl‐ and N‐Acryloyl‐4,4‐Dimethyl‐1,3‐Oxazolidin‐2‐one, Mediated by Chiral Lewis Acids

One‐pot Diels‐Alder reactions of cyclopentadiene with 3‐crotonoyl‐ (2) and 3‐acryloyl‐4,4‐dimethyl‐1,3‐oxazolidin‐2‐one (3), Mediated by chiral Lewis acids, are described. AlCl3, EtAlCl2, Et2AlCl, TiCl4, ZrCl4, SnCl4, SiCl4, and BBr3, modified with derivatives of D‐mannitol, L‐tartaric acid, and (R)‐binaphthol, were applied as chiral promotors. The reaction with dienophile 2, carried out in CH2Cl2 at −78° with high yield, was characterized by excellent π‐face selectivity. In case of the reaction with dienophile 3, the efficiency of the chirality transfer was much lower.