Background: 4-Functionalized isoxazolin-5-ones (isoxazolones) have attracted much
attentions as precursors of functionalized building blocks because the multiple functionalities.
These structural features facilitate the construction of large compound libraries that is important
for development of new functional materials. However, the systematic review article dealing with
nitroisoxazolone has not been published although they exhibit different reactivity from other functionalized
isoxazolones. This review describes the interesting behavior of the nitroisoxazolone
motif and its application to the synthesis of polyfunctionalized compounds.
Methods: Peer-reviewed research literatures describing the chemistry of nitroisoxazolones were
collected, and each paper was appraised using standard criteria. inclusion/exclusion criteria. The
papers were analyzed, and divided according to the reaction patterns.
Results: This review consists of two parts. In the former part, the chemistry of pyridinium salt of
nitroisoxazolone is described, and in the latter part, chemistry of methylnitroisoxazolone is introduced.
Sixty-eight papers were included in this review. Twelve papers deal with pyridinium salt
or its ring-opened product, cyano-aci-nitroacetate. Nine papers mention the chemistry of methylnitroisoxazolones
and derived nitroenamines and nitrile oxide. With regard to each chemistry,
reaction mechanism and reactivity are discussed with citing related literatures.
Conclusion: The findings of this review confirm the importance of nitroisoxazolones in synthetic
chemistry for polyfunctionalized compounds, which are not readily available by alternative methods.
This review will provide useful information and synthetic tools for many chemists studying
synthetic chemistry and medicinal chemistry.