Asymmetric Synthesis of Isoxazol-5-ones and Isoxazolidin-5-ones

Abstract : Isoxazol-5-ones and isoxazolidin-5-ones represent two important classes of heterocycles, with several applications as bioactive compounds and as versatile building blocks for further transformations. Unlike the parent aromatic isoxazoles, the presence of one or two stereocenters in the ring renders their asymmetric construction particularly important. In this review, starting from the description of general features and differences between these two related compound families, we present an overview on the most important enantioselective synthesis strategies to access these heterocycles. Both, chiral metal catalysts and organocatalysts, have been successfully employed for this task in the last years and some of the most promising approaches will be discussed herein. 1) Introduction 2) Isoxazol-5-ones as nucleophiles 3) Asymmetric construction of isoxazolidin-5-ones 4) Arylideneisoxazol-5-ones in conjugated addition 5) Conclusions