About: Pyran is a(n) research topic. Over the lifetime, 5275 publication(s) have been published within this topic receiving 48482 citation(s). The topic is also known as: oxine & pyran.
Papers published on a yearly basis
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.
Abstract: The unprecedented Friedlander reaction of densely functionalized 2-amino-3-cyano-4H-pyrans (1) with cyclohexanone has afforded in one step and good yield 5-amino-4-aryl-3-ethoxycarbonyl-2-methyl-6,7,8,9-tetrahydro-4H-pyran[2,3-b]quinolines (2), novel amino-substituted fused pyran derivatives. These compounds are new tacrine analogues.
07 Apr 1995
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.
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.
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...