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Updated: May 25, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
One-step synthesis of differently bis-functionalized isoxazoles by cycloaddition of carbamoylnitrile oxide with
Nagatoshi Nishiwaki1, Kazuya Kobiro, Shotaro Hirao
1School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada Kami, Kochi 782-8502, Japan. nishiwaki.nagatoshi@kochi-tech.ac.jp
Abstract:
A new protocol for synthesizing different functionalized isoxazoles is provided. Carbamoylnitrile oxide generated from nitroisoxazolone underwent inverse electron-demand 1,3-dipolar cycloaddition with 1,3-dicarbonyl compounds in the presence of magnesium acetate that formed magnesium enolate in situ. Although electron-deficient trifluoroacetoacetate did not undergo this cycloaddition under the same conditions, conversion to sodium enolate furnish the corresponding bis-functionalized trifluoromethylisoxazole. The DFT calculations using B3LYP 6-31G+(d,p) also supported the aforementioned reactivity.
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