A novel acid-catalyzed rearrangement of n-aryl-n′-aryloxyureas to biphenyl derivatives. A [5,5]-rearrangement involving three heteroatoms. |
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Authors: | Yasuyuki Endo Tohru Terashima Koichi Shudo |
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Affiliation: | Faculty of Pharmaceutical Sciences, University of Tokyo, Hongo, Tokyo, Japan |
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Abstract: | In the presence of trifluoroacetic acid, N-phenyl-N′-phenoxyurea (1a) rearranges to N-(4′-hydroxy-2-biphenylyl)urea (2a) and N-carbamoyl-2-hydroxy-diphenylamine (3a). The rearrangement is an intramolecular reaction, and the transition state of the breakage of the N-O bond is deduced to be polarized in the form Nδ- --- Oδ+. The reaction is entirely new and constitutes a fundamental aromatic rearrangement. |
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