An Efficient Synthesis of a Dual PPAR α/γ Agonist and the Formation of a Sterically Congested α-Aryloxyisobutyric Acid via a Bargellini Reaction

A practical synthesis of benzisoxazole 1 and its conversion to α-aryloxyisobutyric acid 2 using 1,1,1-trichloro-2-methyl-2-propanol (chloretone) was developed. Benzisoxazole 1 was formed in high yields by the action of either methanesulfonyl chloride/base upon intermediate oxime 8 or with thionyl ch...

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Published inJournal of organic chemistry Vol. 70; no. 21; pp. 8560 - 8563
Main Authors Cvetovich, Raymond J, Chung, John Y. L, Kress, Michael H, Amato, Joseph S, Matty, Louis, Weingarten, M. David, Tsay, Fuh-Rong, Li, Zhen, Zhou, George
Format Journal Article
LanguageEnglish
Published WASHINGTON American Chemical Society 14.10.2005
Amer Chemical Soc
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Summary:A practical synthesis of benzisoxazole 1 and its conversion to α-aryloxyisobutyric acid 2 using 1,1,1-trichloro-2-methyl-2-propanol (chloretone) was developed. Benzisoxazole 1 was formed in high yields by the action of either methanesulfonyl chloride/base upon intermediate oxime 8 or with thionyl chloride/base, which initially forms cyclic sulfite 10. A highly reactive, short-lived intermediate derived from chloretone was detected by ReacIR and its half-life determined to be ∼5 min. Reaction conditions for the Bargellini reaction were developed that resulted in a 95% yield of 2 from the reaction of highly hindered phenol 1 with chloretone hemihydrate and powdered NaOH in acetone. Thus highly hindered α-aryloxyisobutyric acids can be made in a single step in high yield.
Bibliography:istex:4E6B8622D0503A3103C9F9C2AC934DAF5F3AA36C
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ISSN:0022-3263
1520-6904
DOI:10.1021/jo051027+