Dimroth Rearrangement-Old but not Outdated

Background and Objective: It may seem that the reaction first performed over 120 years ago is an out of date subject on which everything has been said and there is nothing left to be discovered-but first impressions can be deceiving. Even of lately, the Dimroth rearrangement pops up here and there, sometimes chosen deliberately as a method of synthesis, but sometimes it is brought back to life in order to explain unexpected results of experiments. Substrates for the rearrangement are heterocycles, and products are isomeric molecules in which certain heteroatoms (typically N, O, S, rarely Se) change places. Methodology: The reaction may appear separately as a method of synthesis, or it can constitute a stage of the mechanism of a particular reaction. It is a useful tool for obtaining the desired compounds and introducing isotopes (e.g. 15N) into the heterocyclic skeleton of certain molecules (e.g. nucleoside chemistry). Conclusion: The aim of this review is to present a general outlook on the Dimroth rearrangement along with the situations in which it may occur, and to briefly describe its potential applications.