The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Pyrans

heterocyclic compounds that contain an oxygen atom and two conjugated (α-pyrene) or isolated (γ-pyran) double bonds. Pyrans are highly unstable compounds: α-pyran is only known in derivative form, and γ-pyran is a colorless liquid with a boiling point of 84°C (with decomposition; also decomposes rapidly at room temperature).

Dihydropyrans and tetrahydropyrans are most stable and more readily accessible. Important pyran derivatives are αpyrone

and γ-pyrone. The pyran ring is a structural feature of many natural substances. For example, most hexoses (aldoses and ketoses) are essentially six-membered pyranoses.

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References in periodicals archive

Safarzaei, "Potassium sodium tartrate as a versatile and efficient catalyst for the one-pot synthesis of pyran annulated heterocyclic compounds in aqueous media," Research on Chemical Intermediates.

Kinetic and mechanistic investigation of pyrano[2,3-d]pyrimidine formation in the presence of catalyst under novel one-pot three-component reaction

Bis-spiropyrans contain two photochromic spiropyran units in the molecule and achievable opening of two pyran cycles allow one to suggest such compounds as a prototypes for the multistate light-driven molecular switches [7] that can be controllably and reversibly switched between three or more well-distinguished states.

For instance, there were not any examples of observed and well-proved scission of two carbon-oxygen bond in a single bis-spiropyran molecule until quite recently, when we had shown that nonsymmetric bis-spiropyran Figure 2 (1) containing not only indoline but also benzoxazine moiety could undergo opening of two pyran cycles [9].

Theoretical and experimental study of new photochromic bis-spiropyrans with hydroxyethyl and carboxyethyl substituents

Moreover heterocyclic compounds containing pyran ring also present a wide properties of biological activities such as anticancer, spasmolytic, diuretic, anticoagulant [15, 16].

Simple Synthesis of Polyfunctionalized Indoline-Spiro Fused Pyran Derivatives via an Aqueous Multicomponent Reaction

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