Showing papers on "Pyran published in 2006"
TL;DR: Proline has been used as a mild, efficient and neutral catalyst for synthesis of various 4H-benzo[b]pyran derivatives via a one-pot three-component condensation of aromatic aldehydes, active methylene compounds, and dimedone in aqueous media as discussed by the authors.
Abstract: (S)-Proline has been used as a mild, efficient and neutral catalyst for synthesis of various 4H-benzo[b]pyran derivatives via a one-pot three-component condensation of aromatic aldehydes, active methylene compounds, and dimedone in aqueous media. This method offers the advantages of proceeding and neutral and mild conditions, giving high to excellent yields of the products and simple workup.
166 citations
TL;DR: In this article, a molecular iodine catalyzed domino reaction of anilines with cyclic enol ethers, such as 2,3-dihydrofuran and 3,4-dhydro-2 H -pyran, is described.
113 citations
TL;DR: A Pt-catalyzed pentannulation of propargylic esters containing an epoxide moiety achieves the formation of cyclopentenone products as single diastereomers in good yields.
Abstract: A Pt-catalyzed pentannulation of propargylic esters containing an epoxide moiety has been developed. The present transformation achieves the formation of cyclopentenone products as single diastereomers in good yields. The observed products likely form from pyran intermediates that undergo an oxa-6π electrocyclic ring opening to a functionalized dienone, followed by ring closure with an accompanying acyl shift.
83 citations
TL;DR: In this article, the absorption and photoluminescence spectra of two derivatives of 4-dicyanomethylene-2,6-distyryl-4H-pyran were studied both in solution and in aggregation states.
78 citations
TL;DR: The application of easily accessed propargyl vinyl ethers for the synthesis of monocyclic 2H-pyrans was achieved under the reaction conditions, and highly substituted heterocycles were obtained in moderate to excellent yields.
75 citations
TL;DR: Antimony trichloride (SbCl 3 ) was found to be an efficient catalyst for the inverse electron demand imino Diels-Alder reactions of in situ generated N -benzylidenes with 3,4-dihydro-2 H -pyran and 2,3-dhydrofuran to afford pyrano and furano[3,2 c ]quinolines in excellent yields.
57 citations
TL;DR: These compounds appear as promising specific antitubercular agents, since they exhibited neither significant cytotoxicity against mammal cells, nor effect on the growth of various bacteria and fungi.
55 citations
TL;DR: The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity.
Abstract: On the basis of the enaminone methodology, libraries of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones were synthesized by the solid-phase and by the solution-phase parallel synthesis The solution-phase approach turned out to be advantageous over the solid-phase approach The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity
46 citations
TL;DR: Two novel diastereoselective three-component reactions of alkenes or 3,4-dihydro-(2H)-pyran with urea/thiourea-aldehyde mixtures are described.
44 citations
TL;DR: Treatment of these compounds with a primary amine allows rapid access to various N-substituted indenoisoquinolines, whose in vitro anticancer activity and topoisomerase I inhibition have been evaluated.
43 citations
TL;DR: A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 3,4-dihydro-1H-[1]-benzothieno[2,3-c]pyran and 3,8-disubstitution pattern is preferred for the aromatic region.
TL;DR: This paper describes a highly site-, diastereo-, and enantioselective intermolecular radical addition/hydrogen atom transfer to hydroxypyrone pyromeconic and kojic acids that results in densely functionalized pyran moieties.
Abstract: This paper describes a highly site-, diastereo-, and enantioselective intermolecular radical addition/hydrogen atom transfer to hydroxypyrone pyromeconic and kojic acids. The methodology can be extended to the formation of chiral quaternary centers. The products obtained are densely functionalized pyran moieties. The products contain structural features amenable for the introduction of additional substituents.
TL;DR: In this article, the introduction of a substituent into a sterically demanding 2-position of a 3-(4-pyrrolidinophenyl) ring of 3,3-diaryl-3H-naphtho[2,1-b]pyran results in the generation of an additional short wavelength absorption band leading to organic photochromes that appear as dull shades of orange and red.
TL;DR: A series of pyrano[3,2-c]pyran derivatives have been synthesized by the reaction of aromatic aldehyde, malononitrile or cyanoacetate and 4-hydroxy-5-methyl pyran-2-one in EtOH at room temperature catalyzed by KF/Al2O3 as discussed by the authors.
Abstract: A series of pyrano[3,2-c]pyran derivatives have been synthesized by the reaction of aromatic aldehyde, malononitrile or cyanoacetate and 4-hydroxy-5-methylpyran-2-one in EtOH at room temperature catalyzed by KF/Al2O3. The structures of the products were characterized by IR, H NMR and elemental analysis, and 4a was further confirmed by X-ray diffraction analysis.
Patent•
11 Oct 2006
TL;DR: In this article, cationic organoiron(II) pyranylideneacetaldehyde hydrazone complexes were prepared in high yields through condensation reactions of the organometallic hydrazine precursor [CpFe(η6-p-MeC6H4NHNH2)]+PF6- with differently substituted α- and γ-pyranylideacetaldehydes.
Abstract: New cationic organoiron(II) pyranylideneacetaldehyde hydrazone complexes were prepared in high yields through condensation reactions of the organometallic hydrazine precursor [CpFe(η6-p-MeC6H4NHNH2)]+PF6– with differently substituted α- and γ-pyranylideneacetaldehydes. The mononuclear hydrazones were stereoselectively obtained as their (E) isomers about the N=C double bond. All the new compounds were thoroughly characterized by a combination of elemental analysis and spectroscopic techniques (1H and 13C NMR, IR, and UV/Vis), and by a single-crystal X-ray diffraction analysis of the 2-tBu-chromene derivative 5. The spectroscopic data suggest that these complexes have a partial pyrylium character due to the electron-accepting ability of the cationic organometallic fragment and to the electron-releasing properties of the methylenepyran-based donor. The crystal structure of 5 shows that the η6-coordinated tolyl ring and the pyran ring are coplanar (dihedral angle 3.2°), a favorable situation that allows conjugation between the intracyclic oxygen atom and the cationic iron center through the entire hydrazone backbone. Compounds 4–6 are strongly polarized D–π–A systems that exhibit solvatochromic properties, low-lying intramolecular charge-transfer bands in their electronic absorption spectra, and enhanced second-order NLO properties (μβ), as measured by the EFISH technique at 1.907 μm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
TL;DR: A qualitative model for the interaction of these compounds with monoamine transporters is proposed, which will be refined further in the future.
Abstract: In our previous report, we described a novel series of asymmetric pyran derivatives (2S,4R,5R)-2-benzhydryl-5-benzylamino-tetrahydropyran-4-ol and their enantiomers as blockers of monoamine transporters in the brain. In this report, we describe the further exploration of this series of molecules by incorporating functional groups in the molecular template, which should promote the formation of H bonds with the transporters. In addition, a new synthetic scheme for the asymmetric synthesis of disubstituted cis-(6-benzhydryl-tetrahydro-pyran-3-yl)-benzylamine analogues and their biological characterization is reported. All synthesized derivatives were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting the uptake of [(3)H]DA, [(3)H]5-HT, and [(3)H]NE, respectively. The compounds were also tested for their binding potency at the DAT by their ability to inhibit binding of [(3)H]WIN 35, 428. The results indicated that the presence of functional groups, such as -OH, -NH(2), and the bioisosteric 5-substituted indole moiety in both di and trisubstituted compounds, significantly increased their potencies for the SERT and NET, especially for the NET. Among the trisubstituted compounds, (-)-4b exhibited the highest potency for the NET and the SERT (K(i) of 2.13 and 15.3 nM, respectively) and was a serotonin norepinephrine reuptake inhibitor (SNRI). Compound (-)-4a exhibited the highest selectivity for the NET. Among the disubstituted compounds, a number of compounds, such as (-)-9a, (+)-9b, (-)-9b, and (+)-9d, exhibited significant low-nanomolar potencies for the SERT and the NET. Interestingly, compound (-)-9d exhibited appreciable potencies at all three transporters. On the basis of our present and past findings, we propose a qualitative model for the interaction of these compounds with monoamine transporters, which will be refined further in the future.
TL;DR: An expeditious assembly of a C(1)-C(16) subunit of bryostatin 1 is described, which proceeded with complete diastereoselectivity and in excellent isolated yield despite the presence of potentially sensitive functionality in the A-ring segment.
TL;DR: Progress has been made on the advancement of these complex pyran systems toward the natural product saudin and a complete account of these synthetic efforts is presented.
Abstract: The natural product saudin was found to induce hypoglycemia in mice and, therefore, could be an appealing lead structure for the development of new agents to treat diabetes. A diastereoselective tandem Stille-oxa-electrocyclization reaction has been developed which provides access to the core structure of saudin in a rapid and convergent manner. This new reaction has been extended to the convergent preparation of a series of polycyclic pyran systems. Progress has been made on the advancement of these complex pyran systems toward the natural product. A complete account of these synthetic efforts is presented.
TL;DR: In this paper, multicomponent condensations of cyclohexanecarbaldehyde with CH acids, including malonodinitrile, cyanothio(seleno)acetamide, ethyl cyanoacetate, e.g., 1-benzopyrans, 1,4-dihydropyridines, and pyridine, were presented.
Abstract: Multicomponent condensations of cyclohexanecarbaldehyde with CH acids, malonodinitrile, cyanothio(seleno)acetamide, ethyl cyanoacetate, ethyl acetoacetate, thiobarbituric acid, dimedone, resorcinol, and 3-aminophenol, afforded functionalized cyclohexyl-substituted acrylonitriles, 4H-pyrans, 4H-thio(seleno)-pyrans, 1-benzopyrans, 1,4-dihydropyridines, and pyridines.
TL;DR: The oxa-Pictet-Spengler condensation is a valuable tool for the preparation of polysubstituted isochromans and related oxygen-bearing heterocycles as discussed by the authors.
Abstract: Compounds bearing the isochroman ring system are found in natural and synthetic products of interest. The oxa-Pictet- Spengler condensation is a valuable tool for the preparation of polysubstituted isochromans and related oxygen-bearing heterocy- cles. The different stagings of the oxa-Pictet-Spengler reaction, as well as the scope and limitations of this transformation, are dis- cussed.
TL;DR: In this paper, a furo[3,4-c]pyran ring skeleton was constructed starting from the Baylis-Hillman adducts, which was carried out by the successive introduction of propargyl alcohol, radical cyclization, reduction, allylation, and finally ring-closing metathesis reaction.
TL;DR: Surprisingly, the major isomer resulted from approach of the furan from the same face as the protected alcohol, and furnished the corresponding lactone-bridged tricyclic [4 + 4]-cycloadducts with good facial selectivity.
TL;DR: This is the first palladium-mediated tandem C–C bond forming reaction between 3-iodothiophene-2-carboxylic acid and terminal alkynes to afford the unexpected 5-substituted 4-alkynylthieno[2,3- c ]pyran-7-ones in good yields.
TL;DR: In this article, a new pyran (1) was synthesized, which is practically non-emissive when molecularly dissolved in acetone and when added to water induces it to cluster into nanoaggregates, which turns its emission "on" and boosts its luminescence efficiency dramatically.
Abstract: A new pyran (1) is synthesized. When molecularly dissolved in acetone, 1 is practically nonemissive. Addition of water induces it to cluster into nanoaggregates, which turns its emission "on" and boosts its luminescence efficiency dramatically. The color of its emission changes from green to red upon aggregation.
TL;DR: A new synthetic approach to enantiopure pyranonaphthoquinones is described, which undergoes regiospecific Diels-Alder reactions with a variety of oxygenated butadienes to give pyranoquinones including ventiloquinones E, G, L, eleutherin and ent-deoxyquinone A.
Abstract: A new synthetic approach to enantiopure pyranonaphthoquinones is described. (S)-Mellein 10, prepared in 6 steps from (S)-propylene oxide 16, is converted stereospecifically to the (1R,3S)-dimethylpyran 15. The pyran 15 is then converted to the benzoquinone 14, which undergoes regiospecific Diels–Alder reactions with a variety of oxygenated butadienes to give pyranonaphthoquinones including ventiloquinones E, G, L, eleutherin and ent-deoxyquinone A.
TL;DR: In this article, the preparation of 2-Amino-4-aryl-7,7-dimethyl-5-oxo- 4H-5,6,7,8-tetrahydrobenzo[b]pyran derivatives from aromatic aldehyde, malonitrile or cyanoacetate and 5,5dimethyl 1,3-cyclohexanedione in ionic liquid [bmim+][BF4−] was described.
TL;DR: In this paper, a novel reaction of 3-amino-2H-pyran-2-ones and their fused derivatives with hydrazine hydrate leading to the corresponding pyridazine derivatives is reported.
TL;DR: Aldol reaction of enones 1a–c with aldehydes followed by intramolecular conjugate addition proceeded smoothly to afford corresponding 2,3-dihydro-4H-pyran-4-ones in high yields under mild conditions.
TL;DR: In this paper, a new method for the regioselective synthesis of the N-benzoyl-4-(polyfluoroalkyl)anilines 5a-g by thermal Diels-Alder cycloaddition of 5-substituted 3-(benzo-lamino)-6-(poly-poly-alkyl)-pyran-2-ones 1a-e with fluorostyrenes 2 and 7, acetylenes 8a-c or vinyl ethers 10 and 13a and 13b were described.