The use of 4-hetaryliden- and 4-aryliden-5(4H)-oxazolones as dienophiles. Appropriate reagents for the synthesis of cyclic analogues of natural amino acids

This report describes the behavior of 4-hetaryliden- and 4-aryliden-5(4H)-oxazolones as dienophiles in the Diels-Alder reaction with several dienes. The application of this reaction to the synthesis of different conformationally constrained cyclic analogues of natural amino acids of pharmacological interest is also described.