Synthesis of new aza-bicyclic 2-isoxazolines by 1,3-dipolar cycloaddition of endocyclic enecarbamates and enamides with nitrile oxides |
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Authors: | Valderes Moraes de Almeida Alexandre José da Silva Góes Carlos Roque Duarte Correia |
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Institution: | a LASOF-Departamento de Ciências Farmacêuticas, Universidade Federal de Pernambuco-UFPE,CEP 50470-521, Recife-PE, Brazil b Departamento de Antibióticos, UFPE, CEP 50560-901, Recife-PE, Brazil c Instituto de Química, Unicamp, C.P. 6154, CEP 13083-970, Campinas-SP, Brazil |
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Abstract: | Novel aza-bicyclic 2-isoxazolines, 4,5-dihydroisoxazole5,4-b]pyrrolidines, and 4,5-dihydroisoxazole5,4-b]piperidines were synthesized in a highly regioselective manner through a 1,3-dipolar cycloaddition reaction of 5- and 6-membered endocyclic enecarbamates and enamides with several nitrile oxides in good to excellent yields. Hydrogenolysis of 5- and 6-membered Cbz-cycloadducts led to secondary amines, which presented distinctive stabilities. 2-Isoxazoline bisamides were obtained in good yields through a N-benzoylation, followed by ammonolysis of the secondary amine, or directly from ammonolysis of the cycloadducts. |
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Keywords: | Endocyclic enecarbamates Enamides 1 3-Dipolar cycloaddition Nitrile oxides 2-Isoxazolines |
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