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

Abstract

Abstract 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. AlCl 3 , EtAlCl 2 , Et 2 AlCl, TiCl 4 , ZrCl 4 , SnCl 4 , SiCl 4 , and BBr 3 , 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 CH 2 Cl 2 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.