Showing papers on "Pyran published in 1971"

Mouse Resistance Against Foot-and-Mouth Disease Virus Induced by Injections of Pyran.

Abstract: Mouse resistance to foot-and-mouth disease virus (FMDV) was induced by intraperitoneal injections of pyran copolymer. A biphasic pattern of protection occurred with greatest resistance 4 and 48 hr after injection of this polyanion. Viremia was not detectable in pretreated mice challenge-exposed with FMDV. Incubation of virus with pyran did not alter viral infectivity in mice or tissue culture. Serum interferon was demonstrated 1 and 2 days after pyran administration.

Sensitization to Endotoxin by Pyran Copolymer

Abstract: SummaryPyran copolymer markedly sensitizes mice to the lethal effects of endotoxin. The sensitization occurs throughout both phases of RES activity. Pyran action on microsomal enzymes necessary for the metabolism of hexobarbital or antipyrine is not responsible for the sensitization because reversal of this activity with chlorcyclizine does not alter endotoxin sensitization. Preheparinization of pyran-treated mice only slightly prolonged the survival time, but did prevent the kidney damage.

Photosensitized oxygenation of 4H-pyran-4-thiones and 4H-thiopyran-4-thiones

Abstract: Methylene blue-sensitized photo-oxidation of the 4H-pyran-4-thiones (Ia–c) and 4H-thiopyran-4-thiones (Id, e) gives the corresponding ketones (II).

Derivatives of 2h-pyran-3(6h)-ones

Abstract: COMPOUNDS OF THE FORMULA 2-R3,2-R4,3-(O=),6-R1,6-R2-2,3-DIHYDRO-6H-PYRAN IN WHICH R1 AND R2 TOGETHER REPRESENT OXO; OR R1 REPRESENTS HYDROGEN AND R2 REPRESENTS A HYDROXYL, LOWER ALKANOYLOXY, P-NITROBENXOYLOXY OR CHLOROACETOXY, LOWER ALKOXY, LOWER ALKOXY(LOWER)ALKOXY, BENZYLOXY OR TETRAHYDROPYRANYLOXY; R3 REPRESENTS HYDROGEN AND R4 REPRESUBSTITUTED ARYL AND R2 REPRESENTS A HYDROXYL, LOWER ALKOXY, LOWER ALKOXY(LOWER)ALKOXY, BENZYLOXY OR TETRAHYDROPYRANYLOXY; R3 REPRESENTS HYDROGEN AND R4 REPRESENTS LOWER ALKYL, SUBSTITUTED LOWER ALKYL, CYCLO(LOWER) ALKYL, ARYL, SUBSTITUTED ARYL, ARALKYL, SUBSTITUTED ARALKYL; OR R3 AND R4 EACH REPRESENT HYDROGEN OR THE SAME OR DIFFERENT ORGANIC RADICALS DESCRIBED ABOVE; OR R3 AND R4 TOGETHER REPRESENT A CARBOXYLIC RING, ATTACHED IN A SPIRAL FASHION TO THE 2H-PYRAN-3(6H)-ONE RING SO THAT THE CARBON ATOM 2 OF THE PYRANONE RING IS COMMON TO THE CARBOCYLCIC RING. THE COMPOUNDS HAVE ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES, AND METHODS FOR THEIR PREPARATION AND USE ARE ALSO DISCLOSED.

Persulphate oxidation of carboxylic acids. Part IV. Oxidation of o-arylphenoxyacetic acids

Abstract: Oxidation of o-phenylphenoxyacetic acids with persulphate generates ArOCH2· radicals which rapidly cyclise at the C-2′ position to give dibenzo[b,d]pyrans in good yield and dimeric material. The cyclisation can be reversed by pyrolysis of the bis-cyclohexadiene dimer (4) which gives the parent pyran, the linear ArO·CH2·CH2·OAr dimer, and the bis-dibenzopyran (6). Oxidation of dibenzo[b,d]pyran with DDQ yields benzocoumarin and the bis-acetal (8) which is also formed in the persulphate oxidation of o-phenylphenoxyacetic acid. Oxidation of o-(1-naphthyl)phenoxyacetic acids gives largely spiro-dimers and a low yield of pyran. ArOCH2+ cations produced by oxidation of o-phenylphenoxyacetic acid in the presence of an excess of CuII ions, and in other ways, do not cyclise but undergo solvolysis to give phenols.Oxidation of 2,2′-biphenylenedioxyacetic acid results in double cyclisation to a pyranopyran to a slight extent, the main reaction product being a dimer of the spirocyclohexadienone (21) formed via cyclisation at C-1′. When heated, the dimer equilibrates with the monomer and three other isomeric dimers. The monomer (21) can be trapped by Diels–Alder addition with maleic anhydride but not with tetracyanoethylene which effects a rearrangement to 2,2′-methylenedioxybiphenyl.

Photochemical rearrangement of 4H-pyran-4-ones to 2H-pyran-2-ones

Abstract: Irradiation of 2,6-disubstituted-3,5-diphenyl-4H-pyran-4-ones (Ia,b) with a medium-pressure mercury lamp yielded 3,6-diphenyl-4,5-disubstituted-2H-pyran-2-ones (IVa,b).

Novel 5{40 ,6{40 -dihydro-2h-pyran-4{40 -yl prostaglandin ethers

Abstract: Novel 5'',6''-dihydro-2H-pyran-4''-yl prostaglandin ether compounds of the formula WHEREIN R1 is hydrogen or lower alkyl; R2 and R3 are hydrogen when Y is a single bond and R2 R3 are absent when Y is a double bond; R5 is hydrogen or WHEN X is a double bond; and WHEN X is a single bond; WHEN X is a double bond and WHEN X is a single bond; Z1 is a cis or trans -CH CH- or CH2CH2-; Z2 is trans -CH CH- or -CH2CH2-; n is 1 to 5; m is 0 to 5; and the non-toxic salts. The novel compounds possess pharmacological properties as modifiers of smooth muscle activity, gastric secretion, blood pressure, lipolysis and the reproductive system. The compounds also induce labor and menses and they can be used for the relief of asthma and nasal congestion and as platelet anti-aggregation agents.

Photo-oxygenation of 4H-pyran-4-thiones and 4H-thiopyran-4-thiones: reactivity and kinetic characterization

Abstract: Methylene Blue-sensitized photo-oxygenation of the 4H-pyran-4-thiones and 4H-thiopyran-4-thiones gives the corresponding ketones. The relative reactivity (β=k1/k2) of these thioketones to dye-sensitized oxygenation has been determined. The reactivity of the thioketones is the same or higher than that of tetramethylethylene. The quenching of the oxygenation by β-carotene suggests that the reactive species is singlet oxygen for the dyesensitized photo-oxygenation.

Carbamate derivatives of 2h-pyran-3(6h)-one

Abstract: IN WHICH R1 REPRESENTS AN AROMATIC GROUP SUCH AS PHENYL, BENZYLOXPHENYL, 3,4-XYLYL, A-HYDROXYBENZYL, DIPHENYLMETHYL, 4-BIPHENYLYL AND 4''-CHLORO-4-BIPHENYLYL; R2 REPRESENTS HYDROGEN, LOWER ALKYL, CHLOROMETHYL, PHENYL, AND BENZYL; OR R1 AND R2 TOGETHER REPRESENT THE CYCLOHEXANE RING ATTACHED IN SPIRAL FASHION TO THE PYRANONE RING IN SUCH A MANNER THAT CARBON ATOM 2 OF THE PYRANONE RING IS COMMON TO THE CYCOHEXANE RING; R3 IS LOWER ALKYL, PHENYL OR P-CHLOROPHENYL, AND R4 IS HYDROGEN, LOWER ALKYL, PHENYL OR P-CHLOROPHENYL, WITH THE PROVISO THAT WHEN R1 IS A-HYDROXYBENZYL R4 IS HYDROGEN. THE COMPOUNDS ARE USEFUL AS ANTIBACTERIAL, FUNGICIDAL AND COCCIDIOSTATIC AGENTS, AND METHODS FOR THEIR USE AND PROCESSES FOR PREPARING THEM ARE ALSO DISCLOSED. 2-R1,2-R2,3-(O=),6-(R3-N(-R4)-COO-)-3,6-DIHYDRO-2H-PYRAN CARBAMATES OF THE FORMULA

Dibenzopyrans, their isomeric fluorenols and ibenzothiopyrans

Abstract: In a very strongly acidic liquid media, 2,6-diphenylphenol and 2,6-diphenylthiophenol react with most aldehydes and ketones to produce dibenzopyrans or dibenzothiopyrans. The dibenzopyrans, but not the dibenzothiopyrans, can be isomerized to their corresponding fluorenols. Both the pyran and thiopyran ring can be cleaved to convert these materials into phenols which differ from starting phenols because one of the o-phenyl substituents, itself, now has an ortho substituent characteristic of the aldehyde or ketone reactant. Both these phenols and the fluorenols, being phenolic compounds are useful as antioxidants, stabilizers, etc.

Pyran, its analogs, and related compounds

Abstract: The effect of amines (benzylamine, N,N-dimethylethylenediamine, and ethylenediamine) on the tert-butyl ester (I) and tert-butyl amide (II) of chromone-2-carboxylic acid was studied. In contrast to the sterically unhindered derivatives of chromone-2-carboxylic acid, I and II do not undergo amidation or transamidation by reaction with the amines but are converted directly to pyran-ring-opening products. In the case of ethylenediamine, further intramolecular cyclization also occurs to form 5-(o-hydroxyphenyl)-7-carboxy-1,4-diaza-4,6-cycloheptadiene derivatives (VII and IX).

Spiropyrans based on nitrogen heterocycles

Abstract: The corresponding merocyanins (II and III), which are not capable of intramolecular cyclization to form spiropyrans, were obtained by the condensation of quaternary salts of 2- and 4-methylquinoline with o-hydroxyaryl aldehydes. In contrast to II and III, the products of the condensation of 5, 6-dimethylphenanthridinium salts with o-hydroxyaryl aldehydes (IV and V) exist, under the usual conditions, in the spiropyran form, while the derivative of 5-nitrosali-cylaldehyde can be isolated in both the cyclic and merocyanin forms. These differences are associated with the magnitude of the positive charge on the carbon atom which participates in closing the pyran ring.

Water soluble steroids, hydrophilic substd acetoxy derivs

Abstract: The cpds (ROCH2)3C-COO- substd steroids which are water-sol (where R is H, lower acyl or one R = substd pyranyl or polyhydroxycarboxoyl) are prepd by esterification using known methods of the steroid OH gp(s) with tri-(acyloxymethyl)-acetic acid or a reactive deriv and opt saponifying the triacyloxymethyl residue and reacting one of the free OH gps with a reactive deriv of a polyhydroxycarboxylic acid or pyran deriv

Spiroypyrans from nitrogen heterocycles application of the Mo method

Abstract: Calculation by the LCAO MO method showed that the formation and stability of spiropyrans obtained by the condensation of quaternary salts of nitrogen heterocycles with salicylaldehyde depend on the magnitude of the positive charge on the carbon atom at which the pyran ring is closed and on the magnitude of the localization energy of this reaction center. New representatives of spiropyrans based on 5,10-dimethyl-4,9-diazapyrene were synthesized.

Gamboge. Part V. Synthesis of 2′-isopropyl-5′-methylbiphenyl-2,4,6-triol

Abstract: A degradation product of gambogic acid is identified as 2′-isopropyl-5′-methylbiphenyl-2,4,6-triol by comparison with synthetic material. Some related terphenyls and quaterphenyls, and 1,3-dimethoxy-6,6,9-trimethyl-6H-dibenzo[bd]pyran are described.

Pyran derivatives as new perfumes

Abstract: 2-Nonyl acetate, 2-hexyltetrahydrofuran, 4-heptyl-1,3-dioxane, 3-hexyl-4-hydroxytetrahydropyran and its acetate, and decane-1,3-diol and its diacetate were isolated from the products of the reaction of 1-nonene with formaldehyde in acetic and sulfuric acids. The structures of the substances isolated were confirmed by the results of functional analysis and by IR and PMR spectroscopy. The stereoisomeric composition of 3-hexyl-4-hydroxytetrahydropyran and its acetate was established.

Studies on pyran, its analogs, and related compounds: XXVI. An investigation of 4-methylesculetin for the synthesis of substituted 5, 6-dihydroxybenzofurans

Abstract: The bromination of 6,7-dibenzyloxy-4-methylcoumarin has given 6,7-dibenzyloxy-3-bromo-4-methylcoumarin and this has been converted by the Perkin reaction into 5, 6-dibenzyloxy-3-methylbenzofuran and its 2-carboxy derivative. 5, 6-Dihydroxy-3-methylbenzofuran-2-carboxylic acid has been synthesized by the catalytic debenzylation of the latter compound.