A NOVEL ACID-CATALYSED REARRANGEMENT OF N-ARYL-N'-ARYLOXYUREAS TO BIPHENYL DERIVATIVES. A -REARRANGEMENT INVOLVING THREE HETEROATOMS.

Article abstract of DOI:10.1016/S0040-4039(01)81619-1

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 N^δ+(*)O^δ+.