Rearrangements—Synthetic Reactions “Not Liable” to Retrosynthetic Analysis

Molecular rearrangements are not amenable to retrosynthesis because of their complex mechanisms. Still, in some cases retro-rearrangements are a conceivable and useful approach to selected target molecules. In this chapter, arguments for the retrosynthetic approach to some well-known rearrangements, Beckmann, Hofmann, Arndt-Eistert, Favorskii, pinacol and Bayer-Villiger, are presented. The mechanism of these rearrangements is explained. Retrosynthesis and synthesis, which include a specific rearrangement in the key step, are proposed for selected target molecules, among them paracetamol, dinestrol and spasmolytic biphenyl carboxylic acid.