- Activated cyclooctenones are effective dienophiles
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The first Diels-Alder addition of a diene to a cyclooctenone dienophile has been observed. Three activated cyclooctenone dienophiles 1,2, and 3 are studied with a variety of simple and functionalized dienes. Diels-Alder adducts are produced in excellent yields under very mild Lewis acid catalyzed conditions. The usual orientation rules are followed and, as predicted, the products are formed for the most part exclusively by ester-endo addition. The stereoselectivity is influenced by the substitution pattern of the diene in some cases. The factors influencing the stereochemical selectivity of the addition are discussed in some detail.
- Liu,Wang,Kim,Browne,Wang
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Read Online
- Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
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Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
- Santra, Surojit,Maji, Ujjwal,Guin, Joyram
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supporting information
p. 468 - 473
(2020/02/04)
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- A new series of cycloalkane-fused coumarin sulfonates: Synthesis and in vitro antiproliferative screening
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In this paper, we report the synthesis of 14 new cycloalkane-fused tricyclic coumarin sulfonate derivatives. They were examined for in vitro anticancer activity against NCI-57 cancer cell line panel of nine different cancer types. Among all the target analogs, compounds 1c, 1e, and 1n showed the highest activities. Compound 1e exerted the highest percentage growth inhibition (91.91%) against SNB-75 CNS cancer cell line at 10 μM concentration and was more active than carmustineagainst this cell line. Compound 1c also showed strong activity against HT29 colon, ACHN renal, and PC-3 prostate cancer cell lines. Furthermore, compound 1n was selective toward the HT29 colon cancer cell line. Compounds 1c, 1e, and 1n showed superior selectivity against cancer cell lines compared to the noncancerous RAW 264.7 macrophages. The in silico predictions estimate the oral bioavailability, which is in compliance with Lipinski's rule of five.
- El-Gamal, Mohammed I.,Baek, Daejin,Oh, Chang-Hyun
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p. 184 - 191
(2016/02/26)
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- Synthesis of New Tricyclic and Tetracyclic Fused Coumarin Sulfonate Derivatives and Their Inhibitory Effects on LPS-Induced Nitric Oxide and PGE2 Productions in RAW 264.7 Macrophages: Part 2
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The synthesis of a new series of 21 fused coumarin derivatives is described, and the biological evaluation of their in vitro antiinflammatory effects as inhibitors of lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW 264.7 macrophages. The target compounds 1a–u were first tested for cytotoxicity to determine a non-toxic concentration for antiinflammatory screening, so that the inhibitory effects against NO and PGE2 production would not be caused by cytotoxicity. Compounds 1f and 1p were the most active PGE2 inhibitors with IC50 values of 0.89 and 0.95 μM, respectively. Western blot and cell-free COX-2 screening showed that their effects were due to inhibition of both COX-2 protein expression and COX-2 enzyme activity. Their IC50 values against the COX-2 enzyme were 0.67 and 0.85 μM, respectively, which is more potent than etoricoxib. The selectivity indexes of compounds 1f and 1p against COX-2 compared to COX-1 were 41.1 and 42.5, respectively. Compound 1f showed strong inhibitory effects at 5 μM concentration on COX-2 mRNA expression in LPS-induced RAW 264.7 macrophages. Moreover, the tricyclic compounds 1l and 1n as well as the tetracyclic analog 1u were the most potent NO inhibitors, with one-digit micromolar IC50 values. They showed dose-dependent inhibition of inducible nitric oxide synthase (iNOS) protein expression. The tetracyclic derivative 1u was the most potent inhibitor of NO production. It also exhibited a strong inhibitory effect on iNOS mRNA expression in LPS-induced RAW 264.7 macrophages.
- El-Gamal, Mohammed I.,Lee, Woo-Seok,Shin, Ji-Sun,Oh, Chang-Hyun,Lee, Kyung-Tae,Choi, Jungseung,Myoung, Nohsun,Baek, Daejin
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p. 853 - 863
(2016/11/09)
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- Synthesis of tricyclic fused coumarin sulfonates and their inhibitory effects on LPS-induced nitric oxide and PGE2 productions in RAW 264.7 macrophages
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The regulations of NO and PGE2 productions are research topics of interest in the field of antiinflammatory drug development. In the present study, a series of tricyclic fused coumarin sulfonate derivatives was synthesized and evaluated for their abilities to inhibit NO and PGE2 productions in LPS-induced RAW 264.7 macrophages. Among all the target compounds, compound 1g possessing p-(trifluoromethyl)phenyl and fused cycloheptane moieties showed the highest inhibitory effects on NO and PGE 2 productions. Compound 1g not only inhibited COX-2 activity but also reduced expressions of COX-2 and iNOS. Furthermore, ADME profiling showed that compounds 1g, 1j, 1m, and 1n are estimated to be orally bioavailable.
- Jang, Hyeon-Lok,El-Gamal, Mohammed I.,Choi, Hye-Eun,Choi, Ho-Yeong,Lee, Kyung-Tae,Oh, Chang-Hyun
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p. 571 - 575
(2014/01/23)
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- Synthesis, in vitro antiproliferative activity, and in silico studies of fused tricyclic coumarin sulfonate derivatives
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A series of fused tricyclic coumarin sulfonate derivatives was synthesized. Their in vitro antiproliferative activities against a panel of 57 human cancer cell lines of nine different cancer types were tested at the NCI. Compounds 1e, 1f, 1h, 1i, and 1o showed the highest mean percentage of inhibition values over the 57 cell line panel at 10 μM, and they were further tested in 5-dose testing mode to determine their IC50 values. Compounds 1e, 1f, and 1o were more selective against leukemia and colon cancer subpanels, while compounds 1h and 1i showed broad-spectrum anticancer activities. Compounds 1e, 1f, 1h, 1i, and 1o demonstrated high selectivity towards cancer cell lines than RAW 264.7 macrophages. Compound 1h exerted lethal effect over NCI-H522 NSCLC, SK-MEL-5 melanoma, and A498 renal cancer cell lines with percentage of inhibition values of 114.10%, 103.23%, and 100.52% at 10 μM concentration, respectively. Moreover, the IC50 value of compound 1o against HT29 colon cancer cell line was 532 nM. Compounds 1e, 1f, 1h, 1i, and 1o were tested for inhibitory effect over cyclooxygenase-2 (COX-2) enzyme as a possible mechanism of action. Furthermore, in silico studies were conducted to check the compliance of those five compounds with Lipinski's rule of five, and hence estimate their oral bioavailability.
- El-Gamal, Mohammed I.,Oh, Chang-Hyun
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- Synthesis of water-soluble scaffolds for peptide cyclization, labeling, and ligation
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The synthesis and applications of water-soluble scaffolds that conformationally constrain side chain unprotected linear peptides containing two cysteines are described. These scaffolds contain a functionality with orthogonal reactivity to be used for labeling and ligation. This is illustrated by the chemical ligation of two dissimilar constrained peptides via oxime ligation or strain-promoted azide-alkyne cycloaddition in aqueous media.
- Smeenk, Linde E. J.,Dailly, Nicolas,Hiemstra, Henk,Van Maarseveen, Jan H.,Timmerman, Peter
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supporting information; experimental part
p. 1194 - 1197
(2012/05/04)
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- Photopolymerizable vinyl ether based monomeric formulations and polymerizable compositions which may include certain novel spiroorthocarbonates
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Photopolymerizable compositions are provided which are the reaction products of a vinyl ether, a photoinitiator system comprising an iodonium salt, a visible light sensitizer, and an electron donor compound. These monomeric/oligomeric compositions may also include epoxides, polyols, spiroorthocarbonates. One embodiment of the present invention is a polymerizable composition comprised of a vinyl ether, a spiroorthocarbonate, and a photoinitiator system. Another embodiment of the present invention is a polymerizable composition comprised of a vinyl ether, an epoxide, a polyol, and a photoinitiator system. Still another embodiment of the present invention is a polymerizable composition comprised of a vinyl ether, an epoxide, a polyol, a spiroorthocarbonate, and a photoinitiator system. Still further, another embodiment of the present invention is certain novel spiroorthocarbonate compounds. Each of these novel spiroorthocarbonate compounds include at least one epoxy group as a substituent.
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- Metal-mediated two-atom carbocycle enlargement in aqueous medium
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The indium and tin-mediated carbonyl allylations of 1,3-dicarbonyl compounds have been studied in aqueous medium. The study led to the development of a novel two-atom carbocycle-enlargement in water. Five-, six-, seven-, eight-, and twelve-membered rings are enlarged by two carbon atoms into seven-, eight-, nine-, ten-, and fourteen-membered ring derivatives respectively. Tetralone derivatives are similarly expanded to 6-8 fused ring systems; and indanone derivates are expanded to 5-7 fused ring systems. The use of both indium and zinc as the metal mediators provided the ring expansion products successfully. The use of water as a solvent was found to be essential for the ring expansion reaction.
- Li, Chao-Jun,Chen, Dong-Li,Lu, Yue-Qi,Haberman, John X.,Mague, Joel T.
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p. 2347 - 2364
(2007/10/03)
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- Expedient synthesis of unsaturated amide alkaloids from Piper spp: Exploring the scope of recent methodology
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The Sakai aryl aldehyde - cyclic ketone aldol - Grob fragmentation sequence was extended to cinnamaldehyde and cyclohexanone, and the product was elaborated to analogues of the alkaloid piperstachine. The effects of substituents on the reaction involving cinnamaldehyde were studied. The aldol-fragmentation sequence failed with benzaldehyde when cyclooctanone or cyclobutanone was substituted for cyclohexanone or cyclopentanone, and the reasons for this failure were examined. Four-carbon Wittig homologation of the piperonal-cyclobutanone aldol-fragmentation product, a hypothetical route to alkaloids such as retrofractamide A, was thus not viable. Instead, three-carbon homologation of the readily available piperonal-cyclopentanone product, using alkyne chemistry recently disclosed by Lu and Trost, afforded these alkaloids in excellent overall yield. The alkyne isomerization was also used to effect efficient syntheses of pellitorine and several other non-aromatic 2E,4E-dienoic Piper amide alkaloids. The Sakai aryl aldehyde - cyclic ketone aldol - Grob fragmentation sequence was extended to cinnamaldehyde and cyclohexanone, and the product was elaborated to analogues of the alkaloid piperstachine. The effects of substitutents on the reaction involving cinnamaldehyde were studied. The aldol-fragmentation sequence failed with benzaldehyde when cyclooctanone or cyclobutanone was substituted for cyclohexanone or cyclopentanone, and the reasons for this failure were examined. Four-carbon Wittig homologation of the piperonal-cyclobutanone aldol-fragmentation product, a hypothetical route to alkaloids such as retrofractamide A, was thus not viable. Instead, three-carbon homologation of the readily available piperonal-cyclopentanone product, using alkyne chemistry recently disclosed by Lu and Trost, afforded these alkaloids in excellent overall yield. The alkyne isomerization was also used to effect efficient syntheses of pellitorine and several other non-aromatic 2E,4E-dienoic Piper amide alkaloids.
- Strunz, George M.,Finlay, Heather J.
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p. 419 - 432
(2007/10/03)
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