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4-Pyrone (γ-pyrone or pyran-4-one) is an unsaturated cyclic chemical compound with the molecular formula C 5 H 4 O 2.It is isomeric with 2-pyrone. Preparation [ edit ]
2-Pyrone 4-Pyrone. Pyrones or pyranones are a class of heterocyclic chemical compounds. They contain an unsaturated six-membered lactone ring, which has one oxygen atom and an adjacent ketone functional group. [1] There are two isomers denoted as 2-pyrone and 4-pyrone.
The key step of the reaction mechanism involves a cationic 4π-electrocyclic ring closure which forms the cyclopentenone product (See Mechanism below). As the reaction has been developed, variants involving substrates other than divinyl ketones and promoters other than Lewis acids have been subsumed under the name Nazarov cyclization provided ...
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Likewise a 4-hydroxyl pyrylium compound is a γ-pyrone or pyran-4-one (4), to which group belong compounds such as maltol. pyrones. 2-Pyrones are known to react with alkynes in a Diels–Alder reaction to form arene compounds with expulsion of carbon dioxide, for example: [17] Pyrone cycloaddition
4-Pyridone exists a keto-enol tautomerism with its enol tautomer 4-hydroxypyridine. In solution, the keto tautomer is favoured, [4] and the enol tautomer only becomes important in very dilute solutions or solutions of non-polar solvents. However, the enol tautomer is dominant in the gas phase. [5]
The enzyme 2-pyrone-4,6-dicarboxylate lactonase (EC 3.1.1.57, LigI) catalyzes the reversible hydrolytic reaction 2-oxo-2H-pyran-4,6-dicarboxylate + H 2 O = (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate. This enzyme belongs to the Amidohydrolase superfamily of enzymes and is a member of Cluster of Orthologous Groups (COG) 3618. The systematic name of ...
Initial steps in the Buchner–Curtius–Schlotterbeck reaction mechanism. The reaction is then completed either by the reformation of the carbonyl through an 1,2-rearrangement or by the formation of the epoxide. There are two possible carbonyl products: one formed by migration of R 1 (4) and the other by migration of R 2 (5). The relative ...