A novel acid-catalyzed rearrangement of n-aryl-n′-aryloxyureas to biphenyl derivatives. A [5, 5]-rearrangement involving three heteroatoms.

Y Endo, T Terashima, K Shudo

Index: Endo, Yasuyuki; Terashima, Tohru; Shudo, Koichi Tetrahedron Letters, 1984 , vol. 25, # 48 p. 5537 - 5540

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Citation Number: 4

Abstract

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 NO bond is deduced to be polarized in the form N δ----O δ+. The reaction is entirely new and constitutes a fundamental aromatic rearrangement.