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Showing 31-60 of 1014 results for "pyrans" within Papers
Mutlu Dilsiz Aytemir et al.
Archiv der Pharmazie, 337(5), 281-288 (2004-04-20)
In this study, thirteen 3-hydroxy-6-methyl-2-substituted 4H-pyran-4-one derivatives were synthesized for the evaluation of their potential anticonvulsant activity. Mannich bases were prepared by the reaction of substituted piperazine derivatives with allomaltol and formaline. The structures of the synthesized compounds were confirmed
E Abdel-Sattar
Archives of pharmacal research, 21(6), 785-786 (1998-12-30)
The aerial parts of Teucrium yemense yielded two iridoid glycosides. Their structures were elucidated by spectral means as teucardosid and 8-O-acetylharpagid.
Yang Li et al.
Carbohydrate research, 344(16), 2270-2273 (2009-09-19)
X-ray diffraction analyses of iridoid glycoside aucubin (1) and its aglycone aucubigenin (2) are reported. It was found that crystals of 1 are orthorhombic, with P2(1)2(1)2(1) space group, both cyclopentane ring and pyran ring adopt envelope conformations, and the Glc
M M Santos et al.
World journal of microbiology & biotechnology, 28(6), 2435-2440 (2012-07-19)
The aim of this work is to study the conversion of oleuropein-a polyphenol present in olives and olive oil by-products-into hydroxytyrosol, a polyphenol with antioxidant and antibacterial properties. The hydrolysis reaction is performed by lactic acid bacteria. Six bacterial strains
Total synthesis of ambruticin.
Eun Lee et al.
Angewandte Chemie (International ed. in English), 41(1), 176-178 (2002-12-20)
Sayo Nomura et al.
Chemical & pharmaceutical bulletin, 60(1), 94-103 (2012-01-10)
(±)-8-Deisopropyladunctin B, the deisopropyl form of adunctin B, which was isolated from the leaves of Piper aduncum (Piperaceae) collected in Papua New Guinea, was synthesized in 0.77% overall yield in 17 steps from 5,7-dimethoxycoumarin-3-carboxylate. The key step was our original
Xuri Gao et al.
Journal of the American Chemical Society, 125(31), 9308-9309 (2003-08-02)
This Communication reports the optimization of the first catalytic enantio- and diastereoselective hetero[4+2]/allylboration reaction to provide efficient access to alpha-hydroxyalkyl pyran derivatives. The key substrate 3-boronoacrolein pinacolate appears to be an exceptionally favorable heterodiene for use in Jacobsen's enantioselective reverse
David P Temelkoff et al.
Carbohydrate research, 341(10), 1645-1656 (2006-02-28)
Bis(diphenylphosphino)ethane (DPPE) reacts with pyranosyl azides derived from D-glucose and D-glucuronic acid in the presence of acid chlorides to yield the corresponding glycosyl amides. Reaction rates are comparable to those with triphenylphosphine, however, the byproduct phosphine oxide is easily removed
S P Zhao et al.
Yao xue xue bao = Acta pharmaceutica Sinica, 27(11), 845-848 (1992-01-01)
A new bisiridoid glucoside named cornuside was isolated from the fruits of Cornus officinalis Sieb et Zucc. The structure of cornuside has been established by spectroscopic methods (IR, MS, 1HNMR, 13CNMR).
Manish Rawat et al.
Journal of the American Chemical Society, 128(34), 11044-11053 (2006-08-24)
The carbene complex 5-(2,2-dimethyl-2H-chromene)methoxylmethylene chromium pentacarbonyl will undergo a benzannulation reaction with phenylacetylene, 1-pentyne, 3-hexyne, and trimethylsilylacetylene to give 7-hydroxy-10-methoxy-3H-naphtho[2.1-b]pyrans as the primary product. These compounds are difficult to obtain pure due to their sensitivity to air. If the benzannulation
Structurally and stereochemically diverse tetrahydropyran synthesis through oxidative C-H bond activation.
Lei Liu et al.
Angewandte Chemie (International ed. in English), 49(17), 3069-3072 (2010-03-24)
Mild reductive opening of aryl pyranosides promoted by scandium(III) triflate.
Hua-Li Qin et al.
Journal of the American Chemical Society, 129(1), 38-39 (2007-01-04)
M J Jozwiakowski et al.
Pharmaceutical research, 4(5), 398-401 (1987-10-01)
The title compound (6-NO2-BIPS) is adsorptiochromic, becoming colored upon adsorption to a polar surface. Powders of 6-NO2-BIPS adsorbed to silica gel or silicic acid are suspended in glycerin, and the absorption spectrum of the adsorbate is recorded by conventional absorption
Yohko Hanzawa et al.
Journal of oleo science, 61(11), 631-640 (2012-11-10)
3-hydroxy acids, 3-hydroxy-3,7-dimethyloct-6-enoic acid (1) and 3-hydroxy-2,2,3,7-tetramethyloct-6-enoic acid (2), were prepared from 6-methyl-5-hepten-2-one, and they were subsequently used to prepare (2,6,6-trimethyltetrahydropyran-2-yl)acetic acid (3) and 2-methyl-2-(2,6,6-trimethyltetrahydropyran-2-yl)propanoic acid (4), respectively, via cyclization with an acidic catalyst such as boron trifluoride diethyl etherate
Patrick G McGarraugh et al.
Organic letters, 13(24), 6460-6463 (2011-11-17)
Products of a novel iminium-catalyzed oxa-Michael addition undergo a kinetic resolution by a subsequent enamine-catalyzed intermolecular reaction. This is a rare example of kinetic resolution by enamine catalysis and the first organocascade kinetic resolution. This resolution produces enantioenriched 2,6-cis-tetrahydropyrans and
Jean-François Brazeau et al.
Organic letters, 12(1), 36-39 (2009-12-29)
An efficient synthesis of the C1-C17 western unit of narasin was achieved from (S)-Roche ester. Highlights in our synthesis include the successful exploitation of three stereoselective sequences of Lewis acid mediated reaction followed by free-radical-based hydrogen transfer.
Marco Leonetti et al.
Optics letters, 34(24), 3764-3766 (2009-12-18)
We present a detailed study of the gain length in an active medium obtained by doping of DNA strands with 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye molecules. The superior thermal stability of the composite and its low quenching permit one to obtain an optical
U C Reddy et al.
The Journal of organic chemistry, 74(6), 2605-2608 (2009-02-17)
A diastereoselective one-pot, three-component Prins-Friedel-Crafts reaction was developed for the synthesis of 4-aryltetrahydropyran derivatives from the reaction of carbonyl compounds with homoallylic alcohol in the presence of arene promoted by boron trifluoride etherate.
K C Nicolaou et al.
The Journal of organic chemistry, 86(3), 2499-2521 (2021-01-09)
Thailanstatin A and spliceostatin D, two naturally occurring molecules endowed with potent antitumor activities by virtue of their ability to bind and inhibit the function of the spliceosome, and their natural siblings and designed analogues, constitute an appealing family of
Weijun Yao et al.
Organic letters, 12(10), 2422-2425 (2010-05-01)
A cinchona alkaloid-catalyzed domino Michael/hemiacetalization reaction of cyclic beta-oxo aldehydes and aromatic beta,gamma-unsaturated alpha-keto esters, resulting in the formation of spiro-dihydropyran architectures in good yield with high stereoselectivity (up to 97% ee), is presented.
Jinfeng Tian et al.
Journal of separation science, 35(19), 2659-2664 (2012-09-25)
In this study, the bioactive component harpagoside and angroside C in the root of Scrophularia ningpoensis Hemsley was simultaneously separated by high-speed counter-current chromatography (HSCCC). A two-phase solvent system containing chloroform/n-butanol/methanol/water (4:1:3:2, v/v/v/v) was selected following consideration of the partition
G Beke et al.
Journal of natural products, 64(3), 332-340 (2001-03-30)
The coupling reaction of tetraacetylsecologanin with dopamine and its N-benzyl derivative was investigated. In both series, stereoisomers at C-1, as well as regioisomer normal and neo compounds, were formed. Moreover, the N-unsubstituted products were partially lactamized, and the N-benzyl derivatives
J E Lennox et al.
Applied and environmental microbiology, 48(5), 1031-1033 (1984-11-01)
Potassium sorbate and sodium propionate brought about a marked inhibition in the growth of Penicillium expansum and a proportionally greater inhibition in the synthesis of patulin by the mold. At inhibitor concentrations used commercially in bakery products, propionate inhibited growth
Rasha Abdallah Azzam et al.
Chemical & pharmaceutical bulletin, 63(12), 1055-1064 (2015-12-04)
The multi-component reaction of either acetoacetanilide derivative 1a or b with any of the aldehyde derivatives 2a-d and malononitrile 3 in the presence of triethylamine as a catalyst gave the 4H-pyran derivatives 4a-g, respectively. Carrying the same reaction but using
Rui Wang et al.
Preparative biochemistry & biotechnology, 40(3), 171-176 (2010-07-14)
Various alcohols react with 3,4-dihydro-2 H-pyran under mild conditions using a catalytic amount of 1,6-hexanediamine methanesulfonate. It affords the corresponding tetrahydropyranyl ethers in good yields at a faster rate in the absence of solvent.
Minh Pham et al.
The Journal of organic chemistry, 73(2), 741-744 (2007-12-22)
In the presence of indium metal, 3-iodo-2-[(trimethylsilyl)methyl]propene (1) reacts with sequentially added aldehydes to provide cis-2,6-disubstituted tetrahydropyrans in good yields. Evidence suggests that InI, formed upon aldehyde (R1CHO) allylation in aqueous media, acts as a promoter for the silyl-Prins reaction
Pekka Peippo et al.
Journal of agricultural and food chemistry, 52(7), 1824-1828 (2004-04-01)
Anticoccidial drugs are extensively used in the poultry industry to control the infection of the single-cell protozoa of the genus Eimeria. The most commonly used coccidiostats in poultry are the polyether ionophores such as narasin and salinomycin. This paper presents
T Shimizu et al.
Organic letters, 2(14), 2153-2156 (2000-07-13)
The stereoselective total synthesis of reveromycin A (1), a potent inhibitor of eukaryotic cell growth, has been accomplished on the basis of the stereocontrolled construction of the 6,6-spiroketal system, efficient succinylation of the tert-alcohol under high pressure, and the introduction
Bin Li et al.
Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica, 31(2), 133-135 (2006-03-31)
To investigate the chemical constituents from the root of Lasianthus acuminatissimus of Rubiaceae. Normal, reverse phase silica gel, macroporous resin column and HPLC chromatography were used for isolation. Spectroscopic methods (13C-NMR, 1H-NMR, DEPT, EI-MS) were used for identification. Six compounds
Francisca Gutierrez-Rosales et al.
Journal of agricultural and food chemistry, 60(17), 4348-4358 (2012-04-06)
The present study investigates oleuropein metabolism, as well as the involvement of β-glucosidase during the growth, development, and ripening of olive fruit. The results show that in olive fruit the in vivo formation and transformation of oleuropein takes place in
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