Search results for "Furan"
showing 10 items of 667 documents
Synthesis and study of cytotoxic activity of 1,2,4-trioxane- and egonol-derived hybrid molecules against Plasmodium falciparum and multidrug-resistan…
2014
Abstract Malaria and cancer cause the death of millions of people every year. To combat these two diseases, it is important that new pharmaceutically active compounds have the ability to overcome multidrug resistance in cancer and Plasmodium falciparum strains. In search of effective anti-cancer and anti-malaria hybrids that possess improved properties compared to their parent compounds, a series of novel 1,2,4-trioxane-based hybrids incorporating egonol and/or ferrocene fragments were synthesized and tested in vitro against P. falciparum strains, CCRF–CEM cells and the multidrug-resistant P-glycoprotein-over-expressing CEM/ADR5000 cells. The most active compounds against P. falciparum stra…
Regioselective Epoxide Ring Opening. Steroselective Synthesis of a Tetrahydropyran Ring
1998
The stereoselective synthesis of a 2-substituted tetrahydropyran with adjacent alkoxy-bearing stereogenic centre is described. The key steps of this synthesis were the stereoselective epoxidation of an allylic alcohol and the regioselective epoxide ring opening by lithium aluminum hydride. The regio and stereoselective synthesis of a trihydroxyselenide and a trihydroxysulfide is also described. The latter compounds are not suitable for cyclization to tetrahydrofuran ring.
Lewis Acid-Catalyzed [4 + 3] Cycloaddition of 2-(Trimethyl Silyloxy)acrolein with Furan. Insight on the Nature of the Mechanism from a DFT Analysis
2003
[reaction: see text]. The mechanism for the Lewis acid-catalyzed [4 + 3] cycloaddition of 2-(trimethylsilyloxy)acrolein 1 with furan 2 has been studied at the B3LYP/6-31G level. This reaction is a three-step process that is initialized by the nucleophilic attack of 2 to the beta-conjugated position of 1 to give a zwitterionic intermediate IN1. The key step on the formation of the seven-membered ring is the electrophilic attack of the furan residue to the electrophilically activated carbonyl carbon at this intermediate.
Palladium-Catalyzed Skeletal Rearrangement of Spirotricyclic Olefins: A Facile One-Pot Strategy for the Synthesis of a Novel Motif with Cyclopentene …
2013
The first utilization of acyclic cyclopropane bearing spirocyclic olefines for the generation of stereospecific complex fused ring systems with an achiral catalyst is reported.
Terphenyl Derivatives from Allantophomopsis lycopodina.
2016
Three secondary fungal metabolites 1–3 with a benzo[b]naphtho[2,1-d]furan skeleton were isolated from submerged cultures of the ascomycete Allantophomopsis lycopodina. The NMR-based structure elucidation was challenging due to a low H/C ratio of only 0.64 and 0.68, respectively. NMR measurements in two different solvents and the use of NMR experiments such as HSQC-TOCSY and LR-HSQMBC proved to be helpful in this respect. The proposed structures obtained from the comprehensive analysis of the NMR data were verified by comparison of recorded and computed NMR chemical shifts from quantum chemical calculations of several constitutional isomers and were further analyzed with the aid of the DP4 a…
Phytochemical Profile and Apoptotic Activity of Onopordum cynarocephalum.
2012
A phytochemical investigation of acetone and chloroform extracts of the aerial parts of Onopordum cynarocephalum Boiss. et Blanche was carried out. It led to the isolation of two new sesquiterpenes, the elemane aldehyde (2) and the eudesmane (11), together with 15 known compounds: two lignans (1 and 15) and 13 sesquiterpenes (3–10, 12–14, 16, 17). The structures were elucidated by spectroscopic analyses, especially 1D and 2D NMR spectra. The anti-growth effect against three human melanoma cell lines, M14, A375, and A2058, of the different extracts and compounds of O. cynarocephalum was also investigated. Among them, the chloroform extract exhibited the strongest biological activity, while t…
Furoquinolines and dihydrooxazole alkaloids with cytotoxic activity from the stem bark of Araliopsis soyauxii.
2018
Abstract Two new furoquinoline alkaloids, maculine B (1) and kokusaginine B (2) and one new dihydrooxazole alkaloid, veprisazole (3), along with four known compounds namely, N13-methyl-3-methoxyrutaecarpine (4), flindersiamine (5), skimmianine (6) and tilianin (7) were isolated from the methanol extract of the stem bark of Araliopsis soyauxii Engl. by various chromatographic methods. Their structures were determined using spectrometry and spectroscopic techniques including NMR and MS. The cytotoxicity of the new compounds compared to that of doxorubicin, the reference anticancer compound, was determined on a panel of nine cancer cell lines including sensitive and drug resistant phenotypes. …
Natural substances (acetogenins) from the family Annonaceae are powerful inhibitors of mitochondrial NADH dehydrogenase (Complex I).
1994
Natural products from the plants of the family Annonaceae, collectively called Annonaceous acetogenins, are very potent inhibitors of the NADH-ubiquinone reductase (Complex I) activity of mammalian mitochondria. The properties of five of such acetogenins are compared with those of rotenone and piericidin, classical potent inhibitors of Complex I. Rolliniastatin-1 and rolliniastatin-2 are more powerful than piericidin in terms of both their inhibitory constant and the protein-dependence of their titre in bovine submitochondrial particles. These acetogenins could be considered therefore the most potent inhibitors of mammalian Complex I. Squamocin and otivarin also have an inhibitory constant …
Specific interactions of monotetrahydrofuranic annonaceous acetogenins as inhibitors of mitochondrial complex I.
2000
Annonaceous acetogenins (ACG) are a wide group of cytotoxic compounds isolated from plants of the Annonaceae family. Some of them are promising candidates to be a future new generation of antitumor drugs due to the ability to inhibit the NADH:ubiquinone oxidoreductase of the respiratory chain (mitochondrial complex I), main gate of the energy production in the cell. ACG are currently being tested on standard antitumor trials although little is known about the structure activity relationship at the molecular level. On recent studies, the relevance of several parts of the molecule for the inhibitory potency has been evaluated. Due to the great diversity of skeletons included in this family of…
New intermediates for the synthesis of olefin polymerization catalysts: the complexes [M2(µ-Cl)2Cl4(thf)4](M = Ti or V, thf = tetrahydrofuran); Cryst…
1993
The dimeric titanium(III) and vanadium(III) complexes [M2(µ-Cl)2Cl4(thf)4](M = Ti 1 or V 2, thf = tetrahydrofuran) have been prepared by recrystallization of [MCl3(thf)3] from dichloromethane. In the dimers, composed of slightly distorted edge-sharing octahedra, the metal atoms separated by Ti ⋯ Ti and V ⋯ V distances of 3.711 (3) and 3.619(1)A, respectively, are surrounded by two terminal Cl atoms, two oxygen atoms of thf molecules and are linked by two bridging Cl atoms. The geometry around the titanium atoms differs from that around vanadium because the thf molecules and the terminal chlorine atoms are differently located with respect to the bridging chlorine atoms of the M2(µ-Cl)2 unit.…