A dyotropic reaction (from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''dyo'', meaning two) in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clay ...

is a type of

organic reaction Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical rea ...

and more specifically a

pericyclic In organic chemistry, a pericyclic reaction is the type of organic reaction wherein the transition state of the molecule has a cyclic geometry, the reaction progresses in a concerted fashion, and the bond orbitals involved in the reaction overlap ...

valence isomerization In organic chemistry, two molecules are valence isomers when they are constitutional isomers that can interconvert through pericyclic reactions. Benzene There are many valence isomers one can draw for the C6H6 formula benzene. Some were originally ...

in which two

sigma bonds In chemistry, sigma bonds (σ bonds) are the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals. Sigma bonding is most simply defined for diatomic molecules using the language and tools of ...

simultaneously migrate intramolecularly. The reaction type is of some relevance to organic chemistry because it can explain how certain reactions occur and because it is a synthetic tool in the synthesis of organic molecules for example in total synthesis. It was first described by

Manfred T. Reetz Manfred Theodor Reetz (born 13 August 1943) is a German chemist and professor of organic chemistry, who served as director of the Max Planck Institute for Coal Research from 1991 until 2011. His research focuses on directed evolution, enzymes in o ...

in 1971 In a type I reaction two migrating groups interchange their relative positions and a type II reaction involves migration to new bonding sites without positional interchange.

Type I rearrangements

In type I rearrangements (Y-A-B-X conversion to X-A-B-Y) the two migrating groups are oriented

trans Trans- is a Latin prefix meaning "across", "beyond", or "on the other side of". Used alone, trans may refer to: Arts, entertainment, and media * Trans (festival), a former festival in Belfast, Northern Ireland, United Kingdom * ''Trans'' (fil ...

to each other and as a result of the rearrangement they migrate to opposite sides. The first example of a dyotropic rearrangement involving a carbon-carbon bond was reported by Cyril A. Grob and

Saul Winstein Saul Winstein (October 8, 1912 – November 23, 1969) was a Jewish Canadian chemist who discovered the '' Winstein reaction.'' He argued a non-classical cation was needed to explain the stability of the norbornyl cation. This fueled a debat ...

. They observed the interconversion of 2 bromine atoms in a certain

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

. In a straightforward example the two bromine atoms in 3-

tert-butyl In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane. The isomer ''n''-butane can connect in two ways, giv ...

-trans-1,2-dibromohexane mutarotate by heating. In the

transition state In chemistry, the transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest potential energy along this reaction coordinate. It is often marked ...

both bromine atoms connect symmetrically to both carbon atoms on opposite sides and the reaction is concerted. Stepwise mechanisms in dyotropic reactions have also been investigated. : Dyotropic reaction Barili 1970

In organic synthesis an important application is the conversion of 4-substituted-gamma-

lactone Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the co ...

s to

butyrolactone Butyrolactone may refer to: * ''beta''-Butyrolactone * ''gamma''-Butyrolactone (GBL) {{Short pages monitor