Synthesis and dynamic NMR study of ketenimines derived from tert-butyl isocyanide,alkyl 2-arylamino-2-oxo-acetates,and dialkyl acetylenedicarboxylates |
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Authors: | Yavari Issa Nasiri Farough Djahaniani Horieh |
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Institution: | Department of Chemistry, University of Tarbiat Modarres, Tehran, Iran. isayavar@yahoo.com |
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Abstract: | The adduct produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped by alkyl 2-arylamino-2-oxo-acetates. When the aryl group is 2-methyl-6-nitrophenyl or 2,6-di-isopropylphenyl, the product exists as two stable rotamers at room temperature as a result of restricted rotation around the Ar-N single bond. When the aryl group is 1-naphthyl or 8-quinolinyl, dynamic NMR effects are observed in the 1H NMR spectra. The calculated free-energy of activation for interconversion of the rotational isomers in 1-naphthyl and 8-quinolinyl derivatives amounts to about 99+/-2 and 68.5+/-2 kJ mol(-1), respectively. |
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Keywords: | hindered rotation ketenimines peri-interaction tert-butyl isocyanide three-component reaction Ugi reaction |
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