It is shown that the Smiles rearrangement of 3-amino-2,2'-dipyridyl sulfides and their N-acetyl derivatives can be acid, base, or heat catalyzed. In some cases solvent effects were observed, and examples are cited where the compounds underwent rearrangement in the solid state.The Smiles rearrangement2 is generally considered to be an intramolecular nucleophilic aromatic substitution reaction resulting in the migration of an aromatic ring from one hetero atom to another. The change which occurs can be generally represented by the scheme as shown in Fig. 1, where -YH may be -OH, -SH, -NHR, -CONHR, or -S02NHR, while Z may be O, S, SO, or S02.3 The rearrangement has normally been considered to be base catalyzed and, because a rather intriguing interplay of electronic effects arises from ring substituents, some kinetic data also have been reported.4We became interested in this rearrangement in connection with studies on the transmission of substituent effects across the pyridine ring system. The 3-amino-2,2'-dipyridyl sulfides (1) appeared well suited for our purposes, especially since the Smiles rearrangement of this type of compounds has been reported.6 However, our work clearly required a more concise definition of the conditions necessary for rearrangement and this communication describes some results observed in basic, acidic, and neutral media.
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