A pyran compound is a six-membered heterocyclic ring heterocyclic compound containing an oxygen atom, and has two isomers of α-pyran and γ-pyran, and both α-pyran and γ-pyran having no substituent. It has not been found, but derivatives of pyran are widely found in nature, and their derivatives α- and γ-pyrone are mainly present in plants. Benzopyran (chromene), chromone, coumarin, flavonoids, isoflavones, anthocyanins and the like can all be regarded as derivatives of pyran. The electronic structure of pyran is similar to that of benzene. The oxygen atoms in the ring are extremely alkaline, and are stabilized after salt formation. Many important natural substances such as pigments, sugars, antibiotics, and alkaloids contain a ring system of pyran or pyran salts, such as a hemiacetal structure of a six-membered ring in the form of a five-carbon sugar or a six-carbon sugar. Brown sugar. Pyranone corresponds to the product of the oxidation of the methine moiety of the pyran to a carbonyl group. Α-pyrone is a lactone of 5-hydroxy-2,4-pentadienoic acid, which can be hydrolyzed under acid-base catalysis, or can be catalytically hydrogenated to obtain 5-hydroxyvaleric lactone, while carbonyl is not easily reduced. . The fluorene-pyrone can also undergo a diene synthesis reaction. The nature of Γ-pyrone is different, and it has a remarkable aromaticity. Although it is an unsaturated ketone, it does not form hydrazine with phenylhydrazine, and the carbonyl group is not easily reduced. Some important drugs, such as erythromycin, dihydrostreptomycin and the like, contain a tetrahydropyran ring. Many carbohydrates contain a tetrahydropyran ring structure.
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Amino compound
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Oxy-containing amino compound
Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts thereof
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Alcohols, phenols, phenolic compounds and derivatives
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2-cycloalcohol
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Organic derivative of hydrazine or hydrazine
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Terpenoid
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Ether, ether alcohol
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Fluorobenzoic acid series
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