Showing papers on "Pyran published in 2000"
Patent•
06 Sep 2000TL;DR: In this article, photochromic indeno-fused naphthopyran compounds have been described, which have a rating of at least 80 in the Relative ΔOD at Saturation Test and may be represented by the following graphic formula:
Abstract: Described are novel photochromic indeno-fused naphthopyran compounds, examples of which include naphthopyran compounds having a substituted or unsubstituted indeno group, the 2,1 positions of which are fused to the naphtho portion of the naphthopyran as shown below. Also present on the naphthopyran are moderate to strong electron donor substituents at the number 6- and 7-positions and optionally at the 8-position of the pyran ring or a cyclic group fused to the h side of the naphtho portion and weak to moderate electron donor substiuents at the 3-position of the pyran ring. Certain substituents may also be present at the number 5, 8, 9, 10, 11, 12, or 13 carbon atoms of the compounds. These compounds have a rating of at least 80 in the Relative ΔOD at Saturation Test and may be represented by the following graphic formula: Also described are polymeric organic host materials that contain or that are coated with such compounds. Optically clear articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline)type compounds, are also described.
105 citations
TL;DR: SPIKET-P caused tubulin depolymerization in cell-free turbidity assays and exhibited potent cytotoxic activity against cancer cells as evidenced by destruction of microtubule organization, and prevention of mitotic spindle formation in human breast cancer cells.
70 citations
TL;DR: Heber et al. as discussed by the authors showed that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1).
Abstract: Pharmaceutical Institute, Christian-Albrechts University of Kiel, Gutenbergstr. 76, D-24118 Kiel,GermanyTel.: (+49-431) 880-1118, Fax: (+49-431) 880-1352, E-mail: dheber@pharmazie.uni-kiel.de*Author to whom correspondence should be addressed.Received: 7 December 1999 / Accepted: 31 December 1999 / Published: 21 January 2000Abstract: Reaction of 4-hydroxy-6-methyl-2-pyrone (1a) as well as 4-hydroxy-6-methyl-2(1H)-pyridones (1b-d) with arylmethylene malononitriles or arylmethylene methyl cyano-acetates (2a-h) leads to the formation of the very stable 5,6-fused bicyclic 2-amino-4H-pyran derivatives 3a-3af.Keywords: pyrano[4,3-b]pyran, pyrano[3,2-c]pyridine, arylmethylene malononitrile, aryl-methylene cyanoacetate, Michael addition.IntroductionWiener et al. first published [1] that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1). Later, Junek and Aigner [2] found a second case of this heterocyclization via additionof 4-hydroxy-6-methyl-2-pyrone (1a, “triacetic acid lactone”, Scheme 1) to tetracyanoethylene, thuspreparing a substituted 2-amino-4H,5H-pyrano[4,3-b]pyran (B). Many years thereafter, Shaker [3] re-
57 citations
TL;DR: P-TsOH-catalyzed condensation reactions of 1,1-diaryl-2-propyn-1-ol and 2-naphthol in the solid state gave 3, 3-d Diaryl-3H- naphtho[2, 1-b]pyran (6) via Claisen rearrangement.
54 citations
TL;DR: In this paper, a range of enol ethers, linked via their oxygen atom to the anomeric center of a pyran ring system, were shown to undergo oxygen to carbon rearrangement upon treatment with a Lewis acid to give the corresponding 2-carbon substituted products.
Abstract: A range of enol ethers, linked via their oxygen atom to the anomeric centre of a pyran ring system, was shown to undergo oxygen to carbon rearrangement upon treatment with a Lewis acid to give the corresponding 2-carbon substituted products. At low temperature, trimethylsilyl trifluoromethanesulfonate catalysed rearrangements of anomerically linked 6-substituted tetrahydropyranyl enol ethers gave selectively the trans-pyranyl ketones, whereas at higher temperatures selective formation of the cis-pyranyl ketones was observed. In a simple application of the methodology the cis-selective rearrangement was used as the key step in a concise total synthesis of a constituent of civet.
48 citations
TL;DR: A synthesis of the C(29)-C(45) bis-pyran subunit 2 of spongistatin 1 (1a) is described, and features highly diastereoselective alpha-alkoxyallylation reactions using the gamma-alk oxygen substituted allylstannanes 17 and 19, as well as a thermodynamically controlled intramolecular Michael addition to close the F-ring pyran.
Abstract: A synthesis of the C(29)−C(45) bis-pyran subunit 2 of spongistatin 1 (1a) is described. The synthesis proceeds in 19 steps from the chiral aldehyde ent-7, and features highly diastereoselective α-alkoxyallylation reactions using the γ-alkoxy substituted allylstannanes 17 and 19, as well as a thermodynamically controlled intramolecular Michael addition to close the F-ring pyran. The E ring was assembled via the Mukaiyama aldol reaction of F-ring methyl ketone 3 and the 2,3-syn aldehyde 4.
47 citations
41 citations
TL;DR: The structure of 2-methyl-6-methylthio-4-(3,4-methylenedioxyphenyl)benzonitrile (3f) was ascertained by single crystal X-ray diffraction analysis and displayed a variety of weak interactions as discussed by the authors.
Abstract: A convenient synthesis of highly functionalised biaryls 3 and 6 has been delineated through carbanion induced C–C bond formation from 6-aryl-3-cyano-4-substituted-2H-pyran-2-ones (1, 4) and acetone. Extension of this reaction, using aromatic ketones led to (4,6-diarylpyran-2-ylidene)acetonitrile (7) in lieu of the anticipated 2,4-diaryl-6-methylthiobenzonitrile (8). The structure of 2-methyl-6-methylthio-4-(3,4-methylenedioxyphenyl)benzonitrile (3f) was ascertained by single crystal X-ray diffraction analysis and displayed a variety of weak interactions, responsible for the stability and packing of the molecule in the crystalline state.
40 citations
TL;DR: Using monochromatic irradiation in the UV and visible ranges, mathematical methods were devised which were capable of analyzing the system during its dynamic evolution and evaluating the quantum yields of the color‐forming photoreactions.
Abstract: The photokinetic behavior of a photochromic compound, 2,2-spiro-adamantylidene-2H-naphtho[1,2-b]pyran (Py), has been investigated by using monochromatic irradiation in the UV and visible ranges. An unusually complex photochemistry occurs whereby two colored forms (o-quinone–allides) are produced, one of which is thermoreversible whereas the other is not thermoreversible but photoreversible. These are the result of ring opening of the pyran C–O bond to a short lived open-form intermediate which converts to the two different colored forms by twisting around different C–C bonds. Their spectra and molar absorption coefficients were obtained in acetonitrile solution. The kinetic parameters of the thermal bleaching (rate constant and activation energy) and photobleaching (quantum yield) were measured. A plausible reaction mechanism is proposed. Based on this mechanism, mathematical methods were devised which were capable of analyzing the system during its dynamic evolution and evaluating the quantum yi...
37 citations
Patent•
29 Feb 2000TL;DR: In this paper, a photochromic [3H]naphtho[2,1-b]pyran compound with an acetylenic substituent was described.
Abstract: The present invention relates to photochromic [3H]naphtho[2,1-b]pyran compounds containing an acetylenic substituent, process for their manufacture, and photochromic materials and articles obtained therefrom. The invention, in some specific aspects, relates to photochromic compounds having a [3H]naphtho-[2,1-b]pyran structure and bearing an acetylenic group in one of the positions 7 to 10 of the naphthopyran ring structure.
32 citations
Patent•
15 Sep 2000
TL;DR: In this paper, photochromic indeno-fused naphthopyran compounds have been described, which have a rating of at least 80 in the Relative.DELTA.
Abstract: Described are novel photochromic indeno-fused naphthopyran compounds, examples of which include naphthopyran compounds having a substituted or unsubstituted indeno group, the 2,1 positions of which are fused to the naphtho portion of the naphthopyran. Also present on the naphthopyran are moderate to strong electron donor substituents at the number 6- and 7-positions and optionally at the 8-position of the pyran ring or a cyclic group fused to the h side of the naphtho portion and weak to moderate electron donor substituents at the 3-position of the pyran ring. Certain substituents may also be present at the number 5, 8, 9, 10, 11, 12, or 13 carbon atoms of the compounds. These compounds have a rating of at least 80 in the Relative .DELTA.OD at Saturation Test and may be represented by graphic formula (I): Also described are polymeric organic host materials that contain or that are coated with such compounds. Optically clear articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline) type compounds, are also described.
TL;DR: Protection of alcohols as their 2-tetrahydropyranyl ethers and their subsequent hydrolysis can be easily achieved through a microwave irradiated reaction catalysed by iodine.
TL;DR: In this article, a simple mechanistic model for the ring opening/closing reaction in room temperature solution was proposed for 3,3-diphenylnaphtho[2,1-b] pyran in solution.
Abstract: Transient absorption spectroscopy with femtosecond time resolution was used to probe the photochemical ring opening process of 3,3-diphenylnaphtho[2,1-b] pyran in solution. Analysis of the temporal evolution of the spectra from 0.4 ps to 100 ps has allowed us to detect and identify some of the intermediates involved in the photochemical formation of colored photomerocyanine isomers. From these data and those of recent ab initio and semi-empirical calculations on related photochromic systems, a simple mechanistic model was proposed for the ring opening/closing reaction in room temperature solution.
TL;DR: Under the influence of air, a facile 1,4-addition of diethylzinc to acyloxypyranones and alkoxypryanones 1 takes place.
TL;DR: The photokinetic behavior of a photochromic compound, 2,2-spiro-adamantylidene-2H-naphtho[1, 2-b]pyran (Py), has been investigated by using monochromatic irradiation in the UV and visible ranges.
Abstract: The photokinetic behavior of a photochromic compound, 2,2-spiro-adamantylidene-2H-naphtho[1,2-b]pyran (Py), has been investigated by using monochromatic irradiation in the UV and visible ranges. An unusually complex photochemistry occurs whereby two colored forms (o-quinone-allides) are produced, one of which is thermoreversible whereas the other is not thermoreversible but photoreversible. These are the result of ring opening of the pyran C-O bond to a short lived open-form intermediate which converts to the two different colored forms by twisting around different C-C bonds. Their spectra and molar absorption coefficients were obtained in acetonitrile solution. The kinetic parameters of the thermal bleaching (rate constant and activation energy) and photobleaching (quantum yield) were measured. A plausible reaction mechanism is proposed. Based on this mechanism, mathematical methods were devised which were capable of analyzing the system during its dynamic evolution and evaluating the quantum yields of the colorforming photoreactions.
TL;DR: The cyclization of acylated 4-amino-5-aryl-2-(trifluoromethyl)pyridines under the action of P 2 O 5 /POCl 3 smoothly afforded 3-naphthyridine in good yields.
TL;DR: A convergent synthesis of the C29-C44 fragment of spongipyran macrolides is described in this paper, which is based on coupling of the lithiated F-ring sulfone with the E-ring aldehyde, and subsequent reductive desulfonylation to afford the E−F bis (pyran) with high stereoselectivity at the anomeric carbon.
TL;DR: In this paper, new derivatives of 3,5-disubstituted 4H-Pyran-4-one podands (9-15) were prepared by transesterification reaction of dimethyl or diethyl 2,6-dimethyl-4H-pyran, 4-one-3,5dicarboxylate with some glycol, glycol ethers or by nucleophilic substitution of some phenols or glycol ensembles with 3, 5-bis (bromomethyl)-2,6
Abstract: New derivatives of 3,5-disubstituted 4H-Pyran-4-one podands (9-15) were prepared by transesterification reaction of dimethyl or diethyl 2,6-dimethyl-4H-pyran-4-one-3,5-dicarboxylate with some glycol, glycol ethers or by nucleophilic substitution of some phenols or glycol ethers with 3,5-bis (bromomethyl)-2,6-diphenyl-4H-pyran-4-one.
TL;DR: In this article, the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 3-chlorotetrahydrofuran-2,4-dione leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the CH-acid to produce highly functionalized phosphorus ylides containing a furandione ring system in excellent yields.
TL;DR: It is concluded that compoundsIII f andg have a potent molluscicidal activity and induced chemical modification comparable to that induced by physical treatment in the snail’s nucleoprotein, which could possibly be used in immunization againstS.
Abstract: In continuation of the previous work (Fathalla, 1992) on the synthesis of some heterocycles containing uracil moiety, we report herein the incorporation of uracil moiety into cyanopyridine thione, thiosemecarbazone, semicarbazone, cyanopyridine, aminocyano pyridine, isoxazoline, pyrazoline, pyrimidine, triazolo pyrimidine, pyran, selena and thiazole derivatives which might modify their biological activities.
TL;DR: In this article, an N-atom via a modified Curtius reaction provided an easy entry to fused aminocyclopentitols (Schemes 4 and 5), a conformationally restricted cyclopropane-fused analogue of the glycosidase inhibitors mannostatins A (2) and B (3).
Abstract: Treatment of iodolactone 8a, having a cyclopentano[c]pyran skeleton and deriving from aucubin (1) (Scheme 1), with sodium trimethylsilanolate permitted a straightforward rearrangement to bicyclo[3.1.0]hexenes 10a and 10b (Schemes 3 and 4). Introduction of an N-atom via a modified Curtius reaction provided an easy entry to fused aminocyclopentitols (Schemes 4 and 5). Target 4 is a conformationally restricted cyclopropane-fused analogue of the glycosidase inhibitors mannostatins A (2) and B (3).
TL;DR: The enaminone as discussed by the authors is a mixture of 3-Acetyl-4-hydroxy-6-methyl-2H-pyran-2-one and N,N-dimethylformamide dimethyl acetal.
Abstract: 3-Acetyl-4-hydroxy-6-methyl-2H-pyran-2-one 1a condensed with N,N-dimethylformamide dimethyl acetal yielding the enaminone 3a. The latter reacted with a variety of reagents affording pyridine derivatives 11, benzofuranoylpyranes 14 and 17, pyranylpyranes 22, pyranylpyrazole 29a,b and pyranylisoxazole 33.
TL;DR: In this paper, a novel strategy was developed by which chiral oxepinopyran and oxepinooxepane derivatives were synthesised from 1,2-isopropylidene furanoside fused pyran derivatives by the cycloaddition of 4- O -allyl nitrone or nitrile oxide species generated from the Furanoside ring.
TL;DR: In this article, the authors reported a procedure for the effective synthesis of 2-pyrones as well as bromopyrones starting with 2-hydroxy-pyran-3(6H)-ones.
TL;DR: Oxyselenenylation of 3,4-dihydro-2H-pyran with (S,S)-hydrobenzoin and subsequent stereoselective transformations afforded the enantiopure L- and D-arabinose.
Abstract: Oxyselenenylation of 3,4-dihydro-2H-pyran with (S,S)-hydrobenzoin and subsequent stereoselective transformations afforded the enantiopure L- and D-arabinose while a disaccharide, 6-O-(β-D-arabinopyranosyl)-1,2∶3,4-di-O-isopropylidene-α-D-galactopyranose (13) was synthesized from 3,4-dihydro-2H-pyran by utilizing the same methodology.
Patent•
06 Jul 2000TL;DR: In this paper, photochromic compounds corresponding to the formula (I) were used for making glazing for buildings, windscreen, helmet visor and glasses for spectacles.
Abstract: The invention concerns photochromic compounds corresponding to the formula (I) wherein: Th2 represents a bithienyl group in one among positions 5, 6, 8-10 of the naphthenic cycle; R represents a bithienyl or trithienyl group; and R represents a bithienyl, trithienyl, aryl, naphthyl, thienyl, furanyl, pyrrolyl or N-alkyl pyrrolyl group. The invention is useful for making glazing for buildings, windscreen, helmet visor and glasses for spectacles.
TL;DR: In this article, the 2-methylene-dihydrofurans are used as intermediates to yield the observed products, which are obtained by O-or C-attacks on the carbon-carbon triple bond.