ABSTRACT
Rearrangement reactions involve a reshuffling of atom connectivity of the substrate or a reaction intermediate. There are five major classes of chemical reaction types encountered in organic chemistry: additions, eliminations, rearrangements, redox reactions, and substitutions. Most of the named organic reactions that form the workhorse toolbox for organic chemists are categorized uniquely into one of these classes. Modern reactions have attributes that have features of more than one of these classes. Addition reactions involve coupling of two or more components in an acyclic or a cyclic sense. Multi-component reactions are a special sub-class of addition reactions involving at least three substrate structures combining together to produce a product. Redox reactions involve either reduction or oxidation of the substrate where the oxidation states of key atoms in the substrate decrease or increase, respectively. A substitution reaction where the leaving group has a greater molecular weight than the incoming group will generally have a low atom economy.
