Search results for "diene"
showing 10 items of 623 documents
Phosphine-diène and Salicylamidines ligands : coordination chemistry, catalysis and therapy
2017
The subject of this thesis concerns the development of new ligands, their coordination chemistry, and the synthesis of the corresponding metal complexes for catalysis and therapy.The first part of this work relates to the synthesis of diene-phosphine ligands, their saturated analogs, and the corresponding arene-ruthenium complexes. Arene decoordination allows the formation of a cationic bimetallic complex where the ligand is diène-η4/κ-P coordinated to the ruthenium. These complexes have been applied to atom transfer radical addition (ATRA) of CCl4 to styrene. When harsh reaction conditions are used, the superiority of the “diene” complexes is highlighted comparing to saturated analogs.The …
How far the substituent effects in disubstituted cyclohexa-1,3-diene derivatives differ from those in bicyclo[2.2.2]octane and benzene?
2018
Substituents effects in cyclic diene derivatives are studied using quantum chemical modeling and compared to the corresponding effects in aromatic (benzene) and fully saturated (bicyclo[2.2.2]octane) compounds. In particular, electronic properties of the fixed group Y in a series of 3- and 4-X-substituted cyclohexa-1,3-diene-Y derivatives (where Y = NO2, COOH, COO− OH, O−, NH2, and X = NMe2, NH2, OH, OMe, Me, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, NO) are examined using the B3LYP/6-311++G(d,p) method. For this purpose, quantum chemistry models of the substituent effect: cSAR (charge of the substituent active region) and SESE (substituent effect stabilization energy) as well as trad…
Synthesis and biological evaluation of new bicyclic fluorinated uracils through ring-closing metathesis.
2006
Two families of bicyclic fluorinated uracils have been prepared starting from a gem-difluorinated unsaturated nitrile, by means of a ring-closing metathesis reaction to form the new ring, which is fused at the C-5/C-6 or N-1/C-6 positions of the uracil moiety. The selective formation of olefin regioisomers in the metathesis process can be controlled according to the reaction conditions (catalyst, solvent, and temperature). The acaricidal activities of the resulting compounds have also been investigated.
Synthesis of Fluorinated and Non-Fluorinated Bicyclic Amidines through Ring-Closing Metathesis
2011
[EN] An efficient method for the synthesis of fluorinated and non-fluorinated imidazoazepines by a ring-closing metathesis reaction as the key step is described. The influence of the fluorine atoms on the preparation of these bicyclic systems is also studied.
Nacionālisma un militarizācijas izpausmes zemessardzes jaunajos bataljonos
2017
Latvijas nacionālo bruņoto spēku papildspēku grupa “Zemessardze” kopš tās atjoaunošanas 1991.gadā ir pieredzējusi brīvprātīgo plūsmas svārstības. Pēdējo trīs gadu laikā, sākot ar 2014. gadu, ir novērojams straujš kāpums gan jauno karavīru, gan bataljonu skaitā. Krasais kāpums, kas vēl nav sācis norimt un zemessargu pieaugošā klātbūtne sociālo mēdiju tīkolos, kopā ar ikgadējo budžeta pieaugumu nacionālās drošības nozarē, norāda uz centieniem normalizēt militārismu. Balstoties uz daļēji strukturētām intervijām, pētījums iepazīstina zemessargu pašu skatījumu un interpretāciju par viņu būtību, viņu atbildību un lomu sabiedrībā. Pētījums arī apskata dažādos transformāciju procesus, ko ietekmē br…
Theoretical study of the low‐lying states of trans‐1,3‐butadiene
1992
We present extensive ab initio calculations on the low‐lying electronic states of trans‐1,3‐butadiene within the multireference configuration interaction (MRCI) framework by selecting the configurations with a perturbative criterion. The X 1Ag ground state and 1 3Bu, 1 3Ag, 2 1Ag, and 1 1Bu valence excited states have been calculated at a fixed geometry. The results obtained are in good agreement with previous experimental and calculated values, and could help to understand polyene spectroscopy, photochemistry, and photophysics. The advantages of a MRCI method where the most important contributions to the total MRCI wave function, perturbatively selected, are treated variationally, and the …
3H-estradiol and3H-R5020 binding in cytosols of normal and neoplastic human ovarian tissue
1983
High-affinity cytoplasmic estrogen and progesterone receptors in normal and abnormal ovarian tissues were studied. Estradiol receptor was detectable in 65% and progesterone receptor in 36% of the malignant tumors; 39% of all malignant ovarian tissues were estradiol- as well as progesterone-receptor-positive. Tumors were said to be receptor-positive when the receptors bound greater than 5 fM steroid/mg cytosol protein. No correlations were found between receptor status and histopathological diagnosis. In normal ovarian tissues collected at various phases of the menstrual cycle no changes in [3H]-estradiol and [3H]-R5020 binding could be detected. Analysis of the receptor concentration for bo…
Aspidin PB, a phloroglucinol derivative, induces apoptosis in human hepatocarcinoma HepG2 cells by modulating PI3K/Akt/GSK3β pathway.
2012
Aspidin PB, a phloroglucinol derivative isolated from Dryopteris fragrans (L.) Schott, has been previously reported to exert high biological activities. In the present study, we analyzed the apoptotic mechanisms of aspidin PB on human hepatoma cell line, HepG2. Initially, aspidin PB was shown to inhibit the growth of HepG2 cells in a time and dose-dependent manner. After treatment with aspidin PB for 72 h, 48 h and 24 h using MTT assay, the IC(50) values were 10.59 μM, 20.86 μM and 46.59 μM, respectively. Aspidin PB was capable to induce apoptosis, as measured by mitochondrial membrane potential (ΔΨm), acridine orange (AO) staining and propidium iodide (PI)/annexin V-FITC double staining. T…
Syntheses of oxygenated spongiane diterpenes from carvone. Synthesis of dorisenone C
2005
Abstract The synthesis of dorisenone C, a representative member of the spongiane-type diterpene family, is described. The synthesis follows a B→AB→ABC→ABCD approach and is based on the initial preparation of the previously known hydroxy-aldehyde 14 (AB rings) from R -(−)-carvone, followed by an intramolecular Diels–Alder reaction between an oxygenated diene moiety and an acetylenic dienophile for the construction of the C ring (compound 22 ), and adequate manipulation of the Diels–Alder adduct functionality for completion of the spongiane framework.
1,3-Dipolar cycloaddition of diaryldiazomethanes across N-ethoxy-carbonyl-N-(2,2,2-trichloroethylidene)amine and reactivity of the resulting 2-azabut…
2016
Abstract 1,3-dipolar cycloaddition of diaryldiazomethanes Ar2C N2 across Cl3C–CH N–CO2Et 1 yields Δ3-1,2,4-triazolines 2. Thermolysis of 2 leads, via transient azomethine ylides 3, to diaryldichloroazabutadienes [Ar(Ar')C N–CH CCl2] 4. Treatment of 4a (Ar = Ar' = C6H5) and 4c (Ar = Ar' = p-ClC6H4) with NaSR in DMF yields 2-azabutadienes [Ar2C N–C(H) C(SR)2] 5. In contrast, nucleophilic attack of NaStBu on 4 affords azadienic dithioethers [Ar2C N–C(StBu) C(H)(StBu)] (7a Ar = C6H5; 7b Ar' = p-ClC6H4). The reaction of 4a with NaSEt conducted in neat EtSH produces [Ph2C N–C(H)(SEt)–CCl2H] 8, which after dehydrochloration by NaOMe and subsequent addition of NaSEt is converted to [Ph2C N–C(SEt) C…