Showing papers on "Pyran published in 1983"
TL;DR: The pyrans, thiopyrans and selenopyrans can be synthesized using acyclic or cyclic precursors that indicate if a pyran ring closure does or does not occur during synthesis as mentioned in this paper.
Abstract: Publisher Summary This chapter presents the literature for pyrans, thiopyrans, and selenopyrans. Pyran structure refers to a six-membered ring possessing one oxygen, sulfur, selenium, or telurium heteroatom singly bonded in a cyclic system of two double bonds and one tetrahedral atomic center. The pyrans, thiopyrans, and selenopyrans can be synthesized using acyclic or cyclic precursors that indicate if a pyran ring closure does or does not occur during synthesis. Reactions such as (1) oxidation, (2) disproportionation, (3) hydrogenation and reduction, (4) desulfurization of thiopyrans, (5) isomerization, (6) ring-opening reactions, (7) substitution reactions, and (8) conversion to carbocyclic systems (outline the chemical properties of pyrans, thiopyrans, and selenopyrans. Pyrans are very rare as natural products. Only some 2H-pyrans have been isolated from plants. The chapter finally describes the physical properties of triazolopyridines such as electronic spectra, infrared spectra, nuclear magnetic resonance, mass spectra, and some other miscellaneous properties.
74 citations
56 citations
Journal Article•
TL;DR: The results indicated that pyran copolymer elicits primed but not fully activated murine macrophages, which could effect cytostasis of tumor cells; their cytostatic potential was also augmented by addition of endotoxin.
Abstract: The degree of activation of peritoneal macrophages elicited by pyran copolymer (MVE-2) was studied in C57BL/6J mice. When cytotoxicity was examined under endotoxin-free culture conditions, the pyran-elicited macrophages could not complete cytolysis of tumor target cells. The macrophages, however, completed cytolysis when pulsed with endotoxin. These results were obtained when either the interval between injection of the pyran copolymer and harvest of the macrophage or the dose of pyran was varied. The pyran-elicited macrophages expressed five markers considered to be typical of inflammatory macrophages, and bound tumor cells to an augmented degree. The pyranelicited macrophages were capable of secreting a potent cytolytic proteinase when pulsed with endotoxin, but did not secrete cytolytic proteinase spontaneously. The pyran-elicited macrophages, in contrast to inflammatory macrophages, could effect cytostasis of tumor cells; their cytostatic potential was also augmented by addition of endotoxin. Taken together, the results indicated that pyran copolymer elicits primed but not fully activated murine macrophages.
28 citations
TL;DR: In this article, the reactions of β-(2-furanyl)- and β-thienyl)-acrylonitrile with a variety of active methylene reagents are described.
27 citations
TL;DR: In this paper, the behavior of tetrafluoroethylene oligomers with enolate anions derived from ethyl acetoacetate and acetylacetone was investigated.
Abstract: Reactions of compounds that are oligomers of tetrafluoroethylene, with enolate anions derived from ethyl acetoacetate and acetylacetone, give fluorinated pyran derivatives whereas an uncyclised product is obtained from diethyl malonate. Similar reactions with perfluoro-but-2-ene, -cyclohexene, and -cyclopentene give furan or pyran derivatives. The different behaviour of these systems is rationalised.
24 citations
TL;DR: The calcium binding characteristics of antibiotic X‐537A in a lipophilic solvent, acetonitrile (CH3CN), have been studied using circular dichroism (CD) spectroscopy and seem to indicate a rigid part encompassing Ca2+, liganded to 3 oxygens of the molecule.
18 citations
TL;DR: In this article, the first total synthesis of the new compound (21) and the previously isolated acid (7) was achieved in high yield; compounds (8), (9), and (15) were obtained in substantially higher yields than had been achieved by partial synthesis only.
Abstract: Two metabolites of cannabinol (1-hydroxy-6,6,9-trimethyl-3-pentyl-6H-dibenzo[b,d]pyran) in man, 11-hydroxycannabinol (8) and 1-hydroxy-6,6-dimethyl-3-pentyl-6H-dibenzo[b,d]pyran-9-carboxyli acid (7), have been totally synthesized together with three possible metabolites, 11-oxocannabinol (9), 8-hydroxycannabinol (15), and 10-hydroxycannabinol (21). This is the first total synthesis of the novel compound (21) and the previously isolated acid (7) and occurs in high yield; compounds (8), (9), and (15) were obtained in substantially higher yields than had been achieved by partial synthesis only. The key step in these syntheses was the regiospecific formation of the aryl–aryl bond via nucleophilic aromatic substitution of the methoxy group in the o-methoxyaryldihydro-oxazoles (2), (11), and (17) by the Grignard reagent, 2,6-dimethoxy-4-pentylphenylmagnesium bromide. The acid (7) was prepared from the new and possibly psychoactive 9-bromo-9-norcannabinol (6), which was obtained from 4-bromo-2-methoxybenzoic acid. Reduction of the acid (7) with lithium aluminium hydride gave 11-hydroxycannabinol, which was oxidized by Jones reagent to 11-oxocannabinol. 8- and 10-Hydroxycannabinol were synthesized in several steps from 2,5-dimethoxy-p-toluic acid and 2,3-dimethoxy-p-toluic acid, respectively.
18 citations
TL;DR: In this paper, the enamine choisie, obtention soit des alkyl-3 ou -4 -4 dimethyl-2,6 benzoates d'ethyle is given.
Abstract: Selon l'enamine choisie, obtention soit des alkyl-3 ou -4 dimethyl-2,6 benzoates d'ethyle, soit des alkyl-3 dimethyl-2,6 morpholino-4 cyclohexadiene-1,5 carboxylates d'ethyle
17 citations
15 citations
TL;DR: In this article, reaction of methyl- and ethyl-lithium with perfluoro-3,4-dimethylhex-3-ene gives products arising from nucleophilic attack with allylic displacement of fluorine from both CF3 and CF2 positions Phenylmagnesium bromide gives biphenyl via a process which appears to involve one-electron transfer.
Abstract: Reaction of methyl- and ethyl-lithium with perfluoro-3,4-dimethylhex-3-ene (1) gives products arising from nucleophilic attack with allylic displacement of fluorine from both CF3 and CF2 positions Phenylmagnesium bromide gives biphenyl via a process which appears to involve one-electron transfer to (1) Enolate anions undergo substitution in (1) with concomitant cyclisation to give fluorinated pyran derivatives
12 citations
Patent•
06 Sep 1983TL;DR: In this paper, the authors describe a process for stabilization of polymers based on vinyl chloride characterized by the conjoint use of a) 0.005% to 5% by weight relative to the polymer of at least one organic lanthanide derivative chosen from : Lanthanide salts.
Abstract: 1. Process for stabilization of polymers based on vinyl chloride characterized by the conjoint use of a) 0.005% to 5% by weight relative to the polymer of at least one organic lanthanide derivative chosen from : lanthanide salts : of monocarboxylic aliphatic acids having from 2 to 30 carbon atoms or dicarboxylic aliphatic acids having from 3 to 30 carbon atoms, the acids being saturated or containing one or more ethylenic double bonds and being able to contain one or more substituents such as halogen atoms, hydroxyl groups, alkoxy groups having from 1 to 12 carbon atoms, mercapto groups or phenyl, phenoxy, naphthyl or cyclohexyl groups in which the rings are optionally substituted with one or more halogen atoms, hydroxyl groups, alkyl groups having 1 to 6 carbon atoms or alkoxy groups having 1 to 6 carbon atoms, ; of benzoic, 1-naphthoic, 2-naphthoic, cyclopentanecarboxylic, cyclohexanecarboxylic, cyclopentenecarboxylic or cyclohexenecarboxylic acids, the cyclic portions of these acids being able to contain one or more substituents such as halogen atoms, hydroxyl groups, alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 2 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, phenyl, benzyl, phenoxy or cyclohexyl groups, alkoxycarbonyl groups having 2 to 24 carbon atoms or alkenoxycarbonyl groups having 4 to 24 carbon atoms ; of alkyl monoesters (the alkyl group having 1 to 24 carbon atoms) or alkenyl monoesters (the alkenyl group having 3 to 24 carbon atoms) of the dicarboxylic aliphatic acids mentioned above ; of heterocyclic carboxylic acids, in particular those derived from pyridine, furan, thiophene, pyrrole and pyran, which acids can contain one or more substituents such as halogen atoms, hydroxyl groups, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, alkenyl groups having 2 to 12 carbon atoms, alkoxycarbonyl groups having 2 to 24 carbon atoms or alkenoxycarbonyl groups having 4 to 24 carbon atoms ; lanthanide phenolates derived from phenol, 1-naphthol or 2-naphthol, in which the cyclic portions can contain one or more substituents such as halogen atoms, alkyl or alkoxy groups having 1 to 24 carbon atoms, alkenyl groups having 2 to 24 carbon atoms, or phenyl, benzyl, phenoxy or cyclohexyl groups ; lanthanide mercaptides, in particular those derived from thioglycolic or thiomalic acid and their alkyl esters (the alkyl radical having 1 to 12 atoms), alkenyl esters (the alkenyl radical having 2 to 12 carbon atoms), phenyl, benzyl and cyclohexyl esters, and esters of alkanediol (having from 2 to 12 carbon atoms), of dihydroxybenzene and of dihydroxycyclohexane, the cyclic portions of the said esters being able to be substituted with one or more alkyl or alkoxy radicals having from 1 to 6 carbon atoms ; lanthanide chelates of beta-dicarbonyl compounds, in particular those derived from the compounds of general formula (I) : R1 -CO-CHR2 -CO-R3 (I) in which : R1 and R3 , which may be identical or different, denote : a linear or branched alkyl group having 1 to 36 carbon atoms and optionally substituted with one or more halogen atoms, a linear or branched alkenyl group having 3 to 36 carbon atoms and optionally substituted with one or more halogen atoms, an aryl radical or an aryl radical bearing one or more substituents on the aromatic ring, such as : . alkyl radicals having 1 to 6 carbon atoms and optionally substituted with one or more halogen atoms, . alkenyl radicals having 2 to 6 carbon atoms and optionally substituted with one or more halogen atoms, . a nitro group, . a -CHO group, . a -COOH group, . alkoxy groups having 1 to 6 carbon atoms, . -COOR4 groups, R4 being an alkyl radical having 1 to 12 carbon atoms or an alkenyl radical having 2 to 12 carbon atoms, . an OH group, . halogen atoms, an aralkyl radical in which the aliphatic portion contains from 1 to 12 carbon atoms and in which the cyclic portion can contain one or more of the substituents mentioned above, a cycloaliphatic radical containing from 5 to 12 carbon atoms and in which the cyclic portion can contain one or more carbon-carbon double bonds and bear one or more of the substituents mentioned above, an arrangement of several of the radicals mentioned above, the different aliphatic radicals defined above being able to contain one or more oxygen -O- or sulphur -S- atoms or carbonyl -CO- or carboxylate -COO- groups ; R2 denotes a hydrogen atom ; b) 0.01% to 1% by weight relative to the polymer of at least one organic zinc or cadmium derivative chosen from : zinc or cadmium salts of the carboxylic acids from which the lanthanide salts mentioned above are derived ; zinc or cadmium phenolates of the phenols from which the lanthanide phenolates mentioned above are derived ; zinc or cadmium mercaptides of thiocarboxylic acids from which the lanthanide mercaptides mentioned above are derived ; c) at least one of the following secondary heat stabilizers : beta-diketones or beta-ketoaldehydes, aminocrotonic acid esters, 2-phenylindole and its derivatives, 1,4-dihydro-2,6-dimethyl-3,5-bis(alkoxycarbonyl)- pyridines, thioglycolic acid esters, thiomalic acid diesters, beta-keto esters, 1,3-dialkyl-6-aminouracils, 1,3-dialkyl-6-amino-2-thiouracils.
Patent•
06 Apr 1983
TL;DR: In this article, the anti-hypertensive compounds of formula (I): where n is 1 or 2; the lactam group being trans to the OR 5 group; or, when the other of R 1 and R 2 is amino, a pharmaceutically acceptable salt thereof.
Abstract: Anti-hypertensive compounds of formula (I): ##STR1## wherein: one of R 1 and R 2 is nitro, cyano or C 1-3 alkylcarbonyl, and the other is methoxy or amino optionally substituted by one or two C 1-6 alkyl or by C 2-7 alkanoyl; one of R 3 and R 4 is hydrogen or C 1-4 alkyl and the other is C 1-4 alkyl, or R 3 and R 4 together with the carbon atom to which they are attached are C 3-6 spiroalkyl; R 5 is hydrogen, C 1-3 alkyl or C 1-8 acyl; and n is 1 or 2; the lactam group being trans to the OR 5 group; or, when the other of R 1 and R 2 is amino, a pharmaceutically acceptable salt thereof.
TL;DR: In this paper, the reaction of substituted cinnamonitrile derivatives with cyanoacetanilide and ethyl acetoacetate is reported, and several new polyfunctional pyridine and pyran derivatives could be synthesised.
Abstract: The reaction of substituted cinnamonitrile derivatives with cyanoacetanilide and ethyl acetoacetate is reported. Several new polyfunctional pyridine and pyran derivatives could be synthesised. The structures of the prepared compounds and the mechanisms of their formation is reported.
TL;DR: In this article, the authors proposed to combine six-membered ring lactams with 2-hydroxybenzoates to yield 2-acyl-4-butane- and -5-pentanelactams, which can be converted into the saturated [1]benzopyrano[4,3-b]pyrrolones and -pyridinones 14 and 23, respectively.
TL;DR: Viburtinal has been synthesised from 2-cyclopentadienylpropanol via the dihydrocyclopenta[c]pyran (1c), which was itself prepared via regioselective formylation.
Abstract: Viburtinal (2) has been synthesised from 2-cyclopentadienylpropanol (3)via the dihydrocyclopenta[c]pyran (1c), which was itself prepared via regioselective formylation.
TL;DR: In this article, a new synthesis of fused 2 H -pyran derivatives via an electrocyclisation reaction is described which is based on a novel route to o-quinomethide-type precursors.
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TL;DR: In this paper, data on the chemistry of monocyclic, unsaturated, six-membered, oxygen-containing heterocycles, viz., 4H-pyrans, are correlated and systematized for the first time.
Abstract: Data on the chemistry of monocyclic, unsaturated, six-membered, oxygen-containing heterocycles, viz., 4H-pyrans, are correlated and systematized for the first time. The methods for their synthesis, their transformations, and spectroscopic data for them are discussed. The interest in these compounds, which has increased recently, is due to the fact that they are convenient starting compounds for the preparation of important classes of heterocycles such as pyrylium salts and saturated 1,5-diketones. The recyclization of the former and the cyclization of the latter lead to a great diversity of heterocycles that contain various elements (oxygen, nitrogen, sulfur, phosphorus, etc.) in five-, six-, and seven-membered rings and various substituents, including heteroaromatic and heteroorganic substituents. The preparation of 4H-pyrans is realized via three principal pathways: by condensation of carbonyl compounds, by cyclization of saturated 1,5-diketones, and by synthesis on the basis of pyrylium salts. The transformations of 4H-pyrans examined in the review include dehydroaromatization or acidic disproportionation, which lead to pyrylium salts, hydration to give saturated 1,5-diketones, reactions with the participation of the double bonds of the pyran ring, recyclization to give aromatic compounds, and the preparation of radicals and ion radicals. It was shown that 4H-pyrans are used for the solution of theoretical problems, as, for example, in the study of the mechanism of hydride transfer.
TL;DR: Cinetique des reactions de l'ion triphenyl-2,4,6 pyrylium avec butylamine, cyclohexylamines, pyrrolidine piperidine and morpholine conduisant aux amides vinyliques a cycle ouvert correspondants.
Abstract: Cinetique des reactions de l'ion triphenyl-2,4,6 pyrylium avec butylamine, cyclohexylamine, pyrrolidine piperidine et morpholine conduisant aux amides vinyliques a cycle ouvert correspondants. Influence de la nature, primaire ou secondaire, des amines utilisees sur l'etape determinant la vitesse
TL;DR: In this article, the authors considered that perfluoro-2,3-dimethylbutadiene (1) is conjugated and showed that it undergoes free radical addition with methanol, and cycloaddition with diazomethane.
Abstract: Reactions of perfluoro-2,3-dimethylbutadiene (1) with methanol, phenol, and sodium methoxide yield products arising from substitution; with methanol a 1,2-addition product is also observed. Reactions of (1) with enolate anions derived from ethyl acetoacetate and acetylacetone yield pyran derivatives, and an oxepine. The diene (1) undergoes free radical addition with methanol, and cycloaddition with diazomethane. Except under strongly nucleophilic conditions, reactions occur at only one of the double bonds of the diene (1) and, on the basis of this and u.v. spectral data, the diene (1) is considered to be conjugated, contrary to other conclusions.
TL;DR: In this article, a spiropyran was modified with a methoxy group at 8th position of the pyran ring, and the stability of photoresponsive activity was 3.4 times higher than that of [I].
Abstract: 3′, 3′-Dimethyl-6-nitrospiro(2H-1-benzopyran-2,2′-indoline) -1′-propionic acid [I] was modified with a methoxy group at 8th position of the pyran ring. The stability of photoresponsive activity was 3.4 times higher than that of [I]. The new spiropyran is promising for the photocontrol of enzyme activity.
TL;DR: In this article, 2.6-Acetyl-2,2-dimethyl-2H-pyran-fused flavonols have been synthesized.
Abstract: 6-Acetyl-2,2-dimethylchromenes when separately condensed with p-anisaldehyde in the presence of ethanolic NaOH and subsequently oxidized with alkaline hydrogen peroxide without isolating the intermediate chalcones afforded the corresponding 2,2-dimethyl-2H-pyran-fused flavonols respectvely in good yield. Thus, flavonols having free 3-hydroxyl and fused with 2,2-dimethyl-2H-pyran can be synthesized easily.
TL;DR: In this paper, various tetrahydrofuran derivatives were used as modifiers of Ziegler type propylene polymerization catalysts, and the steric and electronic effects introduced by the ether modifiers in the single and binary modifier systems investigated are discussed.
Abstract: Studies of various tetrahydrofuran and tetrahydropyran derivatives as modifiers of Zieglertype propylene polymerization catalysts are reported. Among methyl derivatives, ethers containing two methyl substituents on carbon atoms adjacent to the etheric oxygen provied the best activity-stereospecificity combinations (e.g. 2,5-dimethyltetrahydrofuran (1c) and 2,2,4,4-tetramethyltetrahydrofuran) (4). Significantly better stereospecificity with some loss in activity is realized when bulkier ethers such as isochroman (5) or 2-(tetrahydrofurfuryloxy)tetrahydropyran (6) are used. On the other hand, combination of one of the preceding ethers with a second modifier (bis(tributyltin) sulfide, tributyl phosphite, or triethyl thiosphosphate) results in catalyst systems characterized by very attractive activity-stereospecificity combinations. Systems of this type, containing 1c or 4, exhibit higher activity and about equal or better stereospecificity than the systems modified only with the second modifier; whereas 5 and 6 depress somewhat the activity of the latter systems but provide substantially improved stereospecificity. The steric and electronic effects introduced by the ether modifiers in the single and binary modifier systems investigated are discussed.
TL;DR: The reaction du titre dans des alcools donne les alcoxy-2 p-nitrobenzenesulfonyloxy-3 perhydro pyrannes La stereochimie du processus d'addition depend de l'encombrement sterique de l', attaquant.
Abstract: La reaction du titre dans des alcools donne les alcoxy-2 p-nitrobenzenesulfonyloxy-3 perhydro pyrannes La stereochimie du processus d'addition depend de l'encombrement sterique de l'alcool attaquant
Journal Article•
TL;DR: The structures of two new anticoccidial antibiotics, WS-5995A and B, produced by Streptomyces auranticolor, were determined as I and II, respectively, on the basis of spectral and chemical evidence.
Abstract: The structures of two new anticoccidial antibiotics, WS-5995A and B, produced by Streptomyces auranticolor, were determined as I and II, respectively, on the basis of spectral and chemical evidence.WS-5995A (I), having 5H-benzo[d]naphtho[2,3-b]pyran as its mother skeleton, was synthesized by coupling the diazonium salt prepared from the anthranilic acid (IX) to 3-hydroxy juglone (VIII).