The Dimroth rearrangement is a

rearrangement reaction In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another at ...

taking place with certain

1,2,3-triazole 1,2,3-Triazole is one of a pair of isomeric chemical compounds with molecular formula CHN, called triazoles, which have a five-membered ring of two carbon atoms and three nitrogen atoms. 1,2,3-Triazole is a basic aromatic heterocycle. Synthesis ...

s where endocyclic and

exocyclic In organic chemistry, an alicyclic compound contains one or more all-carbon rings which may be either saturated or unsaturated, but do not have aromatic character. Alicyclic compounds may have one or more aliphatic side chains attached. Cyc ...

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

atoms switch place. This

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, mechanistic organ ...

was discovered in 1909 by

Otto Dimroth Otto Dimroth (28 March 1872 – 16 May 1940) was a German chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an official ...

. :

With R a

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula , and is often represented by the symbol Ph (archaically φ) or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ...

group the reaction takes place in boiling

pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom . It is a highly flammable, weak ...

for 24 hours.

Organic Syntheses ''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and expe ...

, Coll. Vol. 4, p.380 (1963); Vol. 37, p.26 (1957). http://orgsynth.org/orgsyn/pdfs/CV4P0380.pdf This type of triazole has an

amino In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

group in the 5 position. After ring-opening to a

diazo In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds ...

intermediate, C-C bond rotation is possible with 1,3-migration of a proton. Certain 1-alkyl-2-imino

pyrimidine Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The oth ...

s also display this type of rearrangement. : DimrothPyrimidine

In the first step is an

addition reaction In organic chemistry, an addition reaction is an organic reaction in which two or more molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, ...

of water followed by ring-opening of the

hemiaminal In organic chemistry, a hemiaminal (also carbinolamine) is a functional group or type of chemical compound that has a hydroxyl group and an amine attached to the same carbon atom: . R can be hydrogen or an alkyl group. Hemiaminals are intermediat ...

to the aminoaldehyde followed by ring closure. A known drug example of the Dimroth rearrangement includes in the synthesis of Bemitradine 8133-11-3

References

{{Reflist Rearrangement reactions Name reactions