Isoxazoles 3,5-diaryl-, preparation

Liu and Howe employed a photochemical transformation of 3,5-diaryl-isoxazoles to prepare 2,5-diaryloxazoles, which were evaluated as plant growth regulators and herbicides. Photolysis of isoxazoles 126 affords the 2,5-diaryloxazoles 127 in good yield (Scheme 1.34). The authors described this as a potentially general method for preparing analogs such as 127. 

In a search for new isoxazole-based liquid crystalline compounds, a 22-member library of 3,5-diaryl isoxazoles 628 was prepared by parallel synthesis on solid phase (Rink resin) through 1,3-dipolar cycloaddition of supported phenylacetylene units with suitable aryl nitrile oxides generated in situ from hydroxyiminoyl chlorides. Cleavage from the resin under acidic conditions allowed the generation of the cyano moiety <2004TL2277>. 

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