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Pyran

About: Pyran is a research topic. Over the lifetime, 5275 publications have been published within this topic receiving 48482 citations. The topic is also known as: oxine & pyran.


Papers
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Journal ArticleDOI
TL;DR: The Friedlander reaction of densely functionalized 2-amino-3-cyano-4H-pyrans (1) with cyclohexanone has afforded in one step and good yield 5.

287 citations

Journal Article
TL;DR: Pyran (divinyl ether-maleic anhydride) copolymer (NSC 46015) is a polyanion with interferon-inducing and macrophage-stimulating properties, and therefore it has been studied as a possible antitumor agent.
Abstract: Summary Pyran (divinyl ether-maleic anhydride) copolymer (NSC 46015) is a polyanion with interferon-inducing and macrophage-stimulating properties, and therefore it has been studied as a possible antitumor agent. Extensive studies using pyran as an adjuvant to chemotherapy against the LSTRA murine leukemia and the Lewis lung carcinoma were performed. Pyran was effective over a dose range of 0.1 to 100 mg/kg/day. Single and multiple dose schedules were both capable of producing significant numbers of cures or increasing life-span, but pyran was ineffective if used without remission inducing chemotherapy. Various molecular weights of pyran copolymer were compared against NSC 46015 for adjuvant activity as well. In general, NSC 46015 tended to be the most efficacious, but all the pyran sizes that were tested possessed significant activity.

277 citations

Journal ArticleDOI
TL;DR: A simple, straightforward, and highly efficient multicomponent one-pot synthesis of a pharmaceutically interesting diverse kind of functionalized 2-amino-3-cyano-4H-pyrans and pyran-annulated heterocycles has been developed based on a low-cost and environmentally benign commercially available urea as a novel organo-catalyst as mentioned in this paper.
Abstract: A simple, straightforward, and highly efficient multicomponent one-pot synthesis of a pharmaceutically interesting diverse kind of functionalized 2-amino-3-cyano-4H-pyrans and pyran-annulated heterocycles has been developed based on a low-cost and environmentally benign commercially available urea as a novel organo-catalyst. The reaction occurs via tandem Knoevenagel–cyclocondensation of aldehydes, malononitrile, and C–H-activated acidic compounds in aqueous ethanol at room temperature. Following this protocol, it was possible to synthesize 2-amino-3-cyano-pyrano[3,2-c]chromen-5(4H)-ones (4aa–4al), 2-amino-3-cyano-pyrano[4,3-b]pyran-5(4H)-ones (4ba–4be), 2-amino-3-cyano-7,8-dihydro-4H-chromen-5(6H)-one (4ca–4cr), 1H-pyrano[2,3-d]pyrimidine-2,4(3H,5H)-diones (4da–4dd), 2-amino-3-cyano-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromenes (4ea–4ec), 2-amino-3-cyano-4H-pyrans (4fa–4fh), and 1,4-dihydropyrano[2,3-c]pyrazoles (4ga–4gb). The salient features of the present protocol are mild reaction conditions, excellen...

241 citations

Patent
07 Apr 1995
TL;DR: In this article, reversible photochromic naphthopyran compounds are described, examples of which are compounds substituted at the 3 position of the pyran ring with (i) an aryl substituent and (ii) a phenyl substitution having a 5- or 6-member heterocyclic ring fused at the number 3 and 4 carbon atoms of the phenyl substituents.
Abstract: Described are novel reversible photochromic naphthopyran compounds, examples of which are compounds substituted at the 3 position of the pyran ring with (i) an aryl substituent and (ii) a phenyl substituent having a 5- or 6-member heterocyclic ring fused at the number 3 and 4 carbon atoms of the phenyl substituent. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline) type compounds, are also described.

239 citations

Journal ArticleDOI
TL;DR: The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyran products, which exhibit intense fluorescence in the solid state.
Abstract: The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp2)–H/C(sp3)–H and C(sp2)–H/O–H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp2)–H/C(sp3)–H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C(sp2)–H/O–H bonds, affording the 1:2 coupling products. Moreover, some of the naphtho[1,8-bc]pyran products exhibit intense fluorescence in the solid state.

236 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202357
2022183
2021104
2020140
2019137
2018135