Versatile and mild HCl-catalyzed cationic imino Diels-Alder reaction for the synthesis of new tetrahydroquinoline derivatives |
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Authors: | Arnold R Romero Bohórquez Jorge Romero-Daza Mauricio Acelas |
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Institution: | 1. Grupo de Investigación en Compuestos Orgánicos de Interés Medicinal (CODEIM), Parque Tecnológico Guatiguará, Universidad Industrial de Santander, Piedecuesta, Colombiaarafrom@uis.edu.co;3. Grupo de Investigación en Compuestos Orgánicos de Interés Medicinal (CODEIM), Parque Tecnológico Guatiguará, Universidad Industrial de Santander, Piedecuesta, Colombia |
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Abstract: | A simple, inexpensive, and mild one-pot methodology for the synthesis of novel 4-aryl-3-methyl-1,2,3,4-tetrahydroquinolines derivatives using aqueous HCl as catalyst has been developed. The key step involves the formal inverse-electron-demand 4π+ + 2π] cycloaddition reaction of in situ–generated cationic 2-azadienes with arylpropenes (isoeugenol and trans-anethole). Iminium ion intermediates are generated through the condensation between N-benzylanilines and formalin. The products are obtained with good to excellent yields and high trans-diastereoselectivity. Further catalytic hydrogenation (Pd/C) allowed debenzylation to successfully obtain the respective 4-aryl-3-methyl-N-H-tetrahydroquinolines of interest. Recent reports suggest that these compounds could serve as interesting models in pharmacological studies against parasites that cause the most common tropical diseases. |
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Keywords: | Arylpropenes cationic imino Diels–Alder reaction hydrochloric acid tetrahydroquinolines |
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