Münchnone is a mesoionic

Mesoionic

Mesoionic chemical compounds are dipolar five- or six- membered heterocyclic compounds in which both the negative and the positive charges are delocalized...

 heterocyclic

Heterocyclic compound

A heterocyclic compound is a cyclic compound which has atoms of at least two different elements as members of its ring. The counterparts of heterocyclic compounds are homocyclic compounds, the rings of which are made of a single element....

 aromatic chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

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Other Names

In addition to the trivial name münchnone, this molecule has also been referred to as a:

• muenchnone
• munchnone (umlaut omitted)
• 1,3-oxazolium-5-oxide
• 1,3-oxazolium-5-olate
• anhydro-5-hydroxy-1,3-oxazolium hydroxide
• 5-hydroxy-1,3-oxazolium hydroxide, inner salt

Discovery and Utility

The first preparation of a münchnone derivative was reported in 1958 by Lawson & Miles by cyclodehydration of 2-Pyridone-N-acetic acid with acetic anhydride. The azomethine ylide reactivity of münchnones, and their reaction with alkynes

Alkyne

Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...

 in the synthesis of pyrrole

Pyrrole

Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...

s, was first published by Huisgen

Rolf Huisgen

Rolf Huisgen is a German chemist. He was born in Gerolstein and studied in Munich under the supervision of Heinrich Otto Wieland. After completing his Ph.D. in 1943 and his habilitation in 1947, he became professor at the University of Tübingen in 1949...

 et. al. The Huisgen group followed up with a thorough investigation of the chemical properties, reactivity, and utility of münchnones towards the synthesis of many other products. As such, they are typically credited for the discovery of Münchnones. While certain substituted münchnones are stable and easily isolated, the majority, including the parent münchnone itself, are unstable. Münchnones are typically used as 1,3-dipolar cycloaddition

1,3-dipolar cycloaddition

The 1,3-dipolar cycloaddition, also known as the Huisgen cycloaddition or Huisgen reaction, is an organic chemical reaction belonging to the larger class of concerted, pericyclic cycloadditions. It is the reaction between a 1,3-dipole and a dipolarophile, most of which are substituted alkenes, to...

 substrates in the synthesis of pyrroles

Pyrrole

Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...

 by their in situ

In situ

In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...

 generation in the presence of alkynes

Alkyne

Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...

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