Showing papers on "Pyran published in 1972"

Sigmatropic Reactions in Carbanions. I. The 5, 6‐dihydro‐2H‐pyran‐2‐ide cyclopropyl‐enolate rearrangement

Abstract: Lithiation of 5,6-dihydro-2H-pyran (7) gives a mixture of dihydropyranyllithiums 14 and 2. 14 rearranges to 2, and 2 in turn undergoes a [1,4] sigmatropic shift to give the lithium cyclopropyl-enolate 3. Lithiation of nerol oxide 6 gives the lithio derivative 24, which likewise undergoes [1,4] shifts to give cyclopropyl-enolates 28 and 29.

Pyran and Polyribonucleotides: Differences in Biological Activities

Abstract: Maleic anhydride-divinyl ether copolymer (pyran) and the polyribonucleotides are both large polyanions with potent antiviral activity. However, they are biologically quite different. Interferon levels of 100 units or more/ml were associated with antiviral activity of polyribonucleotides. Interferon induction by pyran compounds was not primarily involved in antiviral resistance because preparations that did not induce interferon possessed antiviral activity equal to that of interferoninducing preparations. Both polyriboinosinic-cytidylic acid [poly (rI.rC)] and pyran increased the immune response to sheep erythrocytes in the Jerne hemolytic plaque-forming cell (PFC) assay, but their modes of immunoadjuvant action differed. On peak day, poly (rI.rC)-treated mice demonstrated 5.1 × 10 4 PFC/spleen (557 PFC/10 6 nucleated cells) and pyran-treated mice exhibited 4.5 × 10 4 PFC/spleen (299 PFC/10 6 nucleated cells), as compared with 2.7 × 10 4 PFC/spleen (261 PFC/10 6 nucleated cells) in controls. The compounds also differed in phagocytic alteration; polyribonucleotides did not affect phagocytosis whereas pyran produced a biphasic response. Both polyanions exhibited toxic inhibition of liver microsomal enzyme metabolism of type I and type II drugs. However, whereas pyran sensitized mice 50-fold to the lethal effects of endotoxin, the polyribonucleotides did not significantly sensitize mice to endotoxin.

Pyran-2-ylidene carbene complexes

Abstract: Reaction of the cyclopropenylidene complexes (1) with pyridinium ylides gives stable pyran-2-ylidene complexes (3), a new type of carbene complex stabilised by 6π-electron delocalisation; some reactions of these complexes are described.

Influence of divinyl ether-maleic anhydride (pyran) on foot-and-mouth disease virus infection: Effect on adsorption and multiplication in mouse tissues

Abstract: The mechanism of resistance to foot-and-mouth disease virus (FMDV) which occurs 2 days after divinyl ether-maleic only anhydride (pyran copolymer) treatment but diminishes by the 7th day was investigated. Adsorption of virus by minced infant mouse spleen, muscle, kidney, heart or liver was not affected either at 2 days or 7 days after treatment of the mice with pyran. However,in vitro multiplication of FMDV in minced kidney was affected by pyran at both times. The resistance of mice 2 days after treatment was related to absence of virus in muscle, kidney, and spleen tissues. Seven days after pyran administration, however, FMDV was recovered from muscle and spleen but not kidney. Interferon was recovered from various tissues 2 days but not 7 days after mice were injected with pyran. Other unknown polymer-induced antiviral factors as well as interferon may have been related to the resistance mechanism.

2-(n-2-cyanoethyldithiocarbamylmethylene)-5-hydroxy-4h-pyran-4-one and metal chelates

Abstract: 2 - (N - 2 - CYANOETYLDITHLIOCARBAMYLMETHYLENE) - 5 HYDROXY-4H-PYRAN-4-ONE AND METAL CHELATES THEREOF ARE EFFECTIVE AGENTS FOR CONTROLLING UNDESIRABLE MICROORGANISMS.

Dibenzo(b,d)pyran compounds

Abstract: THE COMPOUNDS ARE DIBENZO (B,)PYRANS HAVING PHARMACOLOGICAL ACTIVITY SUCH AS CENTRAL NERVOUS SYSTEM ACTIVITY AND GASTRIC ACID SECRETION INHIBITORY ACTIVITY. A PREFERRED COMPOUND IS 3-(1,2-DIMETHYLHEPTYL)-HYDROXY-6,6,9-TRIMETHYL-6H-DIBENZO(B,D)PYRAN.

The NMR spectra and conformations of dihydropyran derivatives—II: The conformational energies of carbomethoxy, hydroxymethyl and acetoxymethyl groups at c‐6 of the 5,6‐dihydro‐α‐pyran ring

Abstract: The sum of coupling constants of proton H-6 for conformations H1 and 1H of the 6-substituted 5,6-dihydro-α-pyran derivatives have been determined with the aid of appropriate, conformationally biased compounds. With the use of these values and the PMR spectra of the title compounds, thermodynamic values of their conformational equilibria and the conformational preferences of the carbomethoxy, hydroxymethyl and acetoxymethyl groups, have been evaluated.

Zur Kondensation von Acetonylaceton mit Cyanessigester

Abstract: Bei der Knoevenagel-Kondensation von Acetonylaceton und Cyanessigsaure-athylester mit Piperidinacetat in Benzol entsteht ein Produktgemisch, das in 6 Substanzen zerlegt werden konnte: in das Cyclopenten 5, das symmetrische Bis-Knoevenagel-Produkt 3, das Dihydrofulven 2, das Cyclopenta[b)pyran 1 und das Pyrindinon 13 sowie sein Verseifungs- und Decarboxylierungsprodukt 6. Ihre moglichen Bildungswege werden im Formelschema S. 2599 zusammengefast. Das Cyclopenta[b]pyran wird von verd. Sauren in das Pyrindinon 15 umgelagert, wahrend konz. technische Schwefelsaure den Pyranring unter Bildung des Cyclopentenons 17 spaltet. Condensation of Acetonylacetone with Ethyl Cyanoacetate Knoevenagel condensation of acetonylacetone and ethyl cyanoacetate in benzene catalysed by piperidine acetate leads to the formation of a mixture of products, which has been separated into 6 substances: the cyclopentene 5, the symmetrical bis-Knoevenagel product 3, the dihydrofulvene 2, the cyclopenta[b]pyran 1, and the pyrindinone 13 together with the corresponding saponification and decarboxylation product 6. A reaction scheme summarizing possible pathways is given on page 2599. By dilute acid catalysis the cyclopenta[b]pyran 1 rearranges to the pyrindinone 15, whereas conc. technical sulfuric acid cleaves the pyran ring to form the cyclopentenone 17.

Some reactions with 3-Methyl-1H-naphtho[2,1-b]pyran-1-one

Abstract: 3-Methyl-1H-naphtho[2,1-b]pyran-1-one 1 has been shown to react with various aldehydes to give the styryl derivatives 2. Reaction of 1 with P2S5 gave the thio-derivative 3 which reacted with aldehydes giving the thiostyryl-derivatives 4. Hydroxylamine reacted with 1 giving the isoxazole derivative 5. Hydrazine reacted with 2 giving the pyrazole derivative 6. Compounds 2 have been shown to undergo DIELS-ALDER reaction to give the adducts 7, 8 and 9. When 1 was allowed to react with different dicarboxylic acid anhydrides, the phthalide derivatives 10 were obtained, which on reaction with phenol, gave the dihydroxyphthalophenones 11.

4h-(1)benzothieno(3,2-beta)pyran-4-one-2-carboxylic acids and related compounds

Abstract: COMPOUNDS OF FORMULA I BELOW, POSSESS ANTIANAPHYLACTIC PROPERTIES AND FIND USE IN THE TREATMENT OF ANAPHYLAXIS AND AS ANTI-ALLERGY AGENTS, SUCH AS THE TREATMENT OF ALLERGIC BRONCHIAL ASTHMA.

6h-dibenzo(b,d)pyran-6-ones

Abstract: Novel bis basic esters of 9-substituted phenanthrene and related 9-oxa and 9-aza derivatives thereof, their preparation and use for the prevention and inhibition of viral infections are disclosed.

Process for preparing new heterocyclic derivatives

Abstract: Pyrano(3,4-b)indole, 1H-1,4-oxazino(4,3-a)indole and indeno(2,1c)pyran derivatives characterized by having an amino(lower)alkyl radical attached to the 1 position of the heterocyclic ring system and their corresponding thio analogs are prepared by the condensation of a ketalkylamine with an indole-3-ethanol, indole1-ethanol or indene-3-ethanol respectively or in ketoalkylamine case of the thio analogs the corresponding ethanethiol or ethylthiosulfate salt thereof. The products of this condensation and their corresponding acid addition salts are useful antidepressant and antiulcer agents.

Crystal and molecular structure of 2-bromobenzo[b]indeno[1,2-e]pyran

Abstract: 2-bromobenzo[b]indeno[1,2-e]pyran crystallizes in the monoclinic system: space groupP21/c,a = 7·508,b = 5·959,c= 26·172 A, β = 92·55 °. The structure has been determined by the heavy-atom method and refined by full-matrix least squares toR = 0·072 for 1027 observed reflections.

Research into analogs of pyran and related compounds

Abstract: The reaction of 2-methoxycarbonyl-4, 4-dichloro-2-chromene with 1-piperidino-1-cyclohexene, for example, shows the high alkylating ability of 4, 4-dichlorochromenes toward enamines. In this case, the reaction is accompanied by the transfer of the reaction center in the dichloro compound from the 4-to the 2-position (allyl rearrangement), resulting (after acid hydrolysis) in the formation of 2-methoxycarbonyl-2-(2′-oxo-1′-cyclohexyl)-4-chloro-3-chromene in two diastereoisomeric pairs (IIa and b). The structure of compounds IIa and b is proved by hydrogenation to the diastereoisomeric 2-methoxycar-bonyl-2-(2′-oxo-1′-cyclohexyl) chromans (IIIa and b) and examination of the NMR spectra of the latter. Hydrazides (IVa and b) were obtained from IIa and b, compound IVb then being cyclized to the intramolecular acylhydrazone V, which provides additional support for the structure II.

Reactions of pyrylium salts with nucleophilic agents

Abstract: The reaction of γ-unsubstituted pyrylium salts with alkali-metal cyanides gives cyano- and carboxy-substituted pyrans and pyrylium salts, while the reaction with sodium sulfide gives dipyranyl sulfides. A phthalimide derivative of pyran is obtained from 2,6-diphenylpyrylium perchlorate and potassium phthalimide, while pyrylium cations react with zinc to give the corresponding dipyranyls.

Research into analogs of pyran and related compounds: XXXI. The reduction of 2,2-dimethyl-4-chromanone oximes

Abstract: The reduction of the oximes of 2,2-dimethyl-4-chromanone (I), 2,2, 6-trimethyl-4-chromanone(II), and 2,2, 5, 7, 8-pentamethyl-6-hydroxy-4-chromanone (III) with lithium aluminum hydride has been investigated. The first of these affords the normal reduction product 2,2-dimethyl-4-amino chroman (VI), which was also obtained by catalytic hydrogenation of the oxime. The second oxime is converted into a mixture containing the 4-aminochroman (VII) and the product of reductive ring expansion, 2,2,7-trimethyl-2,3,4,5-tetrahydro-1, 5-benzoxazepine (VIII). From the oxime of III was obtained 2,2,6,8, 9-pentamethyl-7-hydroxy-2,3,4,5-tetrahydro-1,5-benzoxazepine (IX), the structure of which was confirmed by determination of the basicity constants, the NMR spectra, and the preparation of the N-benzoyl derivatives (XI).

Production of 1,3-alkadienes

Abstract: A 3,6-dihydro-2-[H] pyran, which is substituted with 1 or 2 hydrocarbyl groups in the 3 position or with 1 hydrocarbyl group in the 5 position, is converted, at temperatures in the range of 400 DEG -1,000 DEG F., to a 1,3-alkalidene.

Nucleosid‐analoga des 5‐hydroxymethyl‐uracils

Abstract: Die Hydroxymethylgruppe des 5-Hydroxymethyl-uracils (1a) liefert bei der saurekatalysierten Reaktion mit 2.3-Dihydro-furan bzw. -pyran die Verbindungen 2a bzw. 2b. Analog reagiert N1.N3-Dimethyl-5-hydroxymethyl-uracil (1b) zu 2c bzw. 2d. Kondensation von persilyliertem 1a (3) mit 2-Chlor-tetrahydrofuran bzw. -tetrahydropyran fuhrt zu den entsprechenden N3-substituierten Verbindungen 5 bzw. 4. Diese Nucleosid-Analoga setzen sich mit 2.3-Dihydro-furan bzw. -pyran an der 5-standigen Hydroxymethylgruppe zu den Verbindungen 2e–2h um, in denen zwei sauerstoffhaltige Ringe mit Uracil verknupft sind. Diese biologisch interessanten Verbindungen sind Modelle fur das naturlich vorkommende 5-O-glykosidierte 5-Hydroxymethyl-cytosin. Nucleoside Analogues of 5-Hydroxymethyluracil The hydroxymethyl group of 5-hydroxymethyluracil (1a) reacts with 2,3-dihydrofuran and -pyran in the presence of acid catalysts to form 2a and 2b, respectively. N1,N3-Dimethyl-5-hydroxymethyluracil (1b) reacts analogously. By condensation of persilylated 1a (3) with 2-chlorotetrahydrofuran or 2-chlorotetrahydropyran the corresponding N3-substituted derivatives 5 and 4 are obtained. The nucleoside analogues are converted into the compounds 2e–2h by reaction of the hydroxymethyl group with 2,3-dihydrofuran and -pyran, respectively. In these substances two oxygen-containing rings are connected with uracil. These biologically interesting compounds can be regarded as models of the naturally occuring 5-O-glycoside derivatives of 5-hydroxymethylcytosine.

Unsaturated Glycopyranosiduloses: 2(S)-Methoxy-4-benzoyloxy-6(R)-benzoyloxymethyl-5,6-dihydro-2H-pyran-5-one and 2(S)-Benzoyloxymethyl-4-benzoyloxy-6(S)-methoxy-5,6-dihydro-2H-pyran-5-one

Abstract: Publisher Summary This chapter provides an overview of the unsaturated glycopyranosiduloses of the general structure, postulated as intermediates in the formation of γ-pyrones from carbohydrate derivatives, for example, the formation of maltol from the streptose portion of the antibiotic streptomycin or kojic acid from aldos-2-ulose derivatives. They have become readily accessible by treatment of partially acylated aldopyranosides with dimethyl sulfoxide-acetic anhydride, the oxidation of the free hydroxyl group being followed by β-elimination. On dissolution in a strong acid such as trifluoroacetic acid, the enolones undergo spontaneous hydrolysis of the methoxy and C-4 acyloxy groups and rearrange to the more stable γ-pyrone system.