- Sulfuric acid and Amberlyst-H+ catalyzed condensation reactions of renewable keto acids with paraformaldehyde: Synthesis of a new dispiro bis-lactone ring system 2,9,13-trioxadispiro[4.1.4.3]tetradecane-3,6,10-trione
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The sulfuric acid and Amberlyst-H+ catalyzed condensation reactions of renewable feedstock levulinic acid with paraformaldehyde under neat conditions at 80 °C gives 2,9,11,14-tetraoxadispiro[4.1.5.3]pentadecane-3,6-dione in 91-93% yield, in which the structure was confirmed by single crystal X-ray crystallography. A similar condensation reaction between 4-ketopimelic acid and paraformaldehyde at 80 °C gives 2,9,13-trioxadispiro[4.1.4.3]tetradecane-3,6,10-trione. This new dispiro bis-lactone was found to composed of a 1.6 : 1 mixture of isomers with planes of symmetry bisecting the tetrahydro-2H-pyran-4-one rings through the carbonyl groups.
- Amarasekara, Ananda S.,Ha, Uyen,Fonari, Marina S.,Bejagam, Shabari Nath,Margeti?, Davor
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p. 23917 - 23923
(2017/07/10)
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- Bioactive 4-Oxoheptanedioic Monoamide Derivatives of Proteins and Ethanolaminephospholipids: Products of Docosahexaenoate Oxidation
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Oxidative stress causes lipid-derived oxidative modification of biomolecules that has been implicated in many pathological states. Phospholipids containing polyunsaturated fatty acids are major targets of free radical-initiated oxidation. Phospholipids that incorporate docosahexaenoate (DHA) are highly enriched in important neural structures including the brain and retina, where DHA comprises 40% and 60% of total fatty acids, respectively. Oxidative fragmentation of 2-docosahexaenoyl-1-palmityl-sn-glycerophosphocholine generates esters of 4-hydroxy-7-oxohept-5-enoic acid (HOHA) and 4-keto-7-oxohept-5-enoic acid (KOHA) with 2-lysophosphatidylcholine, HOHA-PC, and KOHA-PC. Covalent HOHA adducts that incorporate the primary amino groups of proteins and ethanolamine phospholipids in carboxyethylpyrrole (CEP) derivatives were detected immunologically with anti-CEP antibodies in human tumors, retina, and blood. Now, we generated an anti-OHdiA antibody to test the hypothesis that KOHA adducts, which incorporate the primary amino groups of proteins or ethanolamine phospholipids in 4-oxo-heptanedioic (OHdiA) monoamide derivatives, are present in vivo. However, whereas the anti-CEP antibody is highly specific and does not cross-react with the OHdiA monoamide epitope, the anti-OHdiA monoamide antibody cross-reacted with CEP epitopes making it of little value as an analytical tool for OHdiA monoamides but suggesting the possibility that OHdiA monoamides would exhibit receptor-mediated biological activity similar to that of CEP. An LC-MS/MS method was developed that allows quantification of OHdiA derivatives in biological samples. We now find that KOHA-PC forms OHdiA monoamide adducts of proteins and ethanolamine phospholipids and that OHdiA-protein levels are significantly higher than OHdiA-ethanloamine phospholipid levels in blood from healthy human subjects, 0.45 μM and 0.18 μM, respectively (n = 3, and p = 0.027). OHdiA monoamide epitopes are angiogenic, causing TLR2-dependent adhesion and tube formation by human umbilical vein endothelial cells. OHdiA monoamide epitopes are only slightly less potent than CEP epitopes that contribute to the pathological angiogenesis of age-related macular degeneration and tumor growth.
- Guo, Junhong,Hong, Li,West, Xiaoxia Z.,Wang, Hua,Salomon, Robert G.
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p. 1706 - 1719
(2016/10/24)
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- The Esterase Catalysed Resolution of Lactones and Spirodilactone
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The pig liver esterase catalysed hydrolysis of spirodilactone and γ-phenyl-γ-butyrolactone gives optically active products (>90percent e.e., after 50percent reaction).However, the similarly substituted acyclic ester analogues of the lactone do not exhibit enantioselectivity suggesting that the acylation step shows the selectivity.Racemic spirodilactone can be converted, in principle, entirely into one of its enantiomers.
- Barton, Patrick,Page, Michael I.
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p. 2317 - 2318
(2007/10/02)
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- 179. Die Oxidation von 3-(1-Nitro-2-oxocycloalkyl)propanal
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Oxidation of the title compound 1 with KMnO4 under neutral condiitons led to the corresponding acid 2, 5-(2,3,4,5-tetrahydro-2-nitro-5-oxo-2-furyl)pentanoic acid (4), and 4-oxononadioic acid (6).On the basis of experimental results the mechanism of the formation of 4 is discussed (Scheme 1).Oxidation of 1 with KMnO4 under basic conditions gave 6 which was transformed to (E)-4,5-dihydro-5-(2'-oxocyclopentyliden)furan-2(3H)-one (12) with benzene/TsOH (Scheme 3).In contrast to this result the corresponding 4-oxoheptandioic acid (22) yields 1,6-dioxaspirononan-2,7-dione (23) only (Scheme 4).
- Zuercher, Alois,Hesse, Manfred
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p. 1937 - 1943
(2007/10/02)
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