Synthesis of ethyl 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylate via regioselective dipolar cycloaddition |
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Authors: | Michael A. Schmidt Kishta KatipallyAntonio Ramirez Omid SoltaniXiaoping Hou Huiping ZhangBang-Chi Chen Xinhua QianRajendra P. Deshpande |
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Affiliation: | a Chemical Development, R&D, Bristol-Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08903, United States b Discovery Chemistry, R&D, Bristol-Myers Squibb Company, Route 206 and Province Line Road, Princeton, NJ 08543, United States |
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Abstract: | Efforts to prepare ethyl 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylate (1) by developing a regioselective 1,3-dipolar cycloaddition between phenyl nitrile oxide and various 4,4,4-trifluoromethyl crotonates are described. The substitution at the C2-position of crotonate dipolarophile 4 significantly influenced the regiochemistry and yield of the cycloaddition. Enol and enol ether-based crotonates underwent regioselective cycloadditions with phenyl nitrile oxide to provide 4-trifluoromethyl isoxazoles in good yields. |
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Keywords: | Heterocycles 1,3-Dipolar cycloaddition Regioselective Fluorine |
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