Phosphine-Catalyzed [3+2] Cycloadditionsof 2-Phenyl-4-Arylidene-5(4H)-Oxazoloneswith Allenoate: A Concise Synthesis of Aspartic Acid Analogues

A Ph3P-catalyzed (3+2) cycloaddition of 2-phenyl-4- arylidene-5(4H)-oxazolones with benzyl 2,3-butadienoate has been developed for the efficient synthesis of structurally diverse and con- formationally constrained aspartic acid analogues.