Exo diastereoselective Diels-Alder reactions of (R)-2-phenyl-4-methylene-oxazolidin-5-one

Article abstract of DOI:10.1016/S0040-4020(01)80808-5

The thermally induced Diels-Alder reactions of (R)-2-phenyl-4-methylene-oxazolidin-5-one 2 and substituted 1,3-cyclohexadienes and substituted 1,3-butadienes gives exo diastereomeric Diels-Alder adducts. In some cases the initially formed adducts undergo epimerization at the amino-acetal carbon, however the stereochemical integrity of the quaternary α-amino acid stereogenic centre is maintained and Diels-Alder adducts can be obtained in high enantiomeric purity (>90% ee). The stereochemistry of these adducts has been elucidated by single crystal X-ray structure determinations and 2D ¹H NMR analysis.