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1.
Keshavamurthy S 《The Journal of chemical physics》2005,122(11):114109
This work establishes a firm relationship between classical nonlinear resonances and the phenomenon of dynamical tunneling. It is shown that the classical phase space with its hierarchy of resonance islands completely characterizes dynamical tunneling and explicit forms of the dynamical barriers can be obtained only by identifying the key resonances. Relationship between the phase space viewpoint and the quantum mechanical superexchange approach is discussed in near-integrable and mixed regular-chaotic situations. For near-integrable systems with sufficient anharmonicity the effect of multiple resonances, i.e., resonance-assisted tunneling, can be incorporated approximately. It is also argued that the presumed relation of avoided crossings to nonlinear resonances does not have to be invoked in order to understand dynamical tunneling. For molecules with low density of states the resonance-assisted mechanism is expected to be dominant. 相似文献
2.
Oksana V. Midyanko Vasilii Yu. Galla Vladimir M. Buzash Vukadin M. Leovac 《Transition Metal Chemistry》1990,15(2):156-159
Summary The ligand, potassium bicyclo[2.2.1]-hept-5-en-endo-2-oyl-hydroxylamine-3-carboxylate-monohydrate, KHL·H2O2 and its M(HL)2 complexes, [{Fe(HL)2}2SO4], K[FeL2] and K2[ML2] (M=MnII, FeII, CoII, NiII, CuII and ZnII) were prepared and characterized. For all, except the sulphate complex of iron(III), a monomeric octahedral configuration was postulated and this is realized through the coordination of oxygen atoms of the carboxylic, carbonyl and oxime group of two mono-or di-anion ligands. The dianionic form of the ligand is the result of deprotonation of the carboxylic group and mide-alcohol form of the hydroxamic group. For the sulphate-containing iron(III) complex a dimeric coordination is proposed with two monoanions of the organic ligand (the carbonyl oxygens are not coordinated) and the bridging SO4 group. The relative degree of covalency of the metal-carboxylic oxygen bond is 10.6–45.2% and increases in the order: MnIIIIIIIIIIIII. The complexes have been characterized by elemental and t.g. analysis and i.r. spectra. 相似文献
3.
Srihari Kusuma W. David Wilson David W. Boykin 《Journal of heterocyclic chemistry》1985,22(5):1229-1232
A series of five 8-substituted α-[bis(2-hydroxyethyi)aminoethyl]naphtho[2,1-b]thiophenes 7 and a series of seven N-(3-dimethylaminopropyl)-8-substituted naphtho[2,1-b]thiophene-4-carboxamides 8 have been synthesized. The naphtho[2,1-b]thiophene-4-carboxylic acids 4 were prepared by photooxidative cyclization of α-(2-thienyi)-β-arylacrylic acids 3. The carboxylic acids 4 were converted by a conventional five step route involving α-bromoketone intermediates to the a-[bis(2-hydroxyethyl)aminomethyl]-8-substituted naphtho-[2,1-6]thiophene-4-methanols 7 and by a standard two-step amide preparation to the N-(3-dimethylaminopropyl)-8-substituted naphtho[2,1-6]thiophene-4-carboxamides 8 . 相似文献
4.
The stereoselective total synthesis of (?)-panaxjapyne-C was accomplished in a convergent fashion. The synthesis utilizes the readily available enantiomers l-(+)-diethyltartrate and d-(?)-diethyltartrate and involves a Cadiot–Chodkiewicz coupling reaction, and an Ohira–Bestmann reaction as the key steps. 相似文献
5.
Galla Raju Rajesh NomulaKallaganti V.S. Ramakrishna Palakodety Radha Krishna 《Tetrahedron letters》2014
The first total synthesis of (6Z,9S)-3,4-trans-9-hydroxy-3-methyldodec-cis-6-en-4-olide and (6Z)-3,4-trans-9-oxo-3-methyldodec-cis-6-en-4-olide was achieved in a convergent pathway. The salient features of our synthesis include Ohira–Bestmann reaction, regioselective alkyne addition to terminal epoxide, TEMPO/BAIB mediated oxidative lactonization, and partial hydrogenation. 相似文献
6.
The first total synthesis of (Z,11S)-3,4-trans-11-hydroxy-3-methyldodec-cis-6-en-4-olide and (Z)-3,4-trans-11-oxo-3-methyldodec-cis-6-en-4-olide was accomplished using Jacobsen hydrolytic kinetic resolution, Ohira–Bestmann reaction, regioselective alkyne addition to terminal carbon atom of epoxide, intramolecular TEMPO/BAIB mediated oxidative lactonization and partial hydrogenation as the key steps. 相似文献
7.
8.
Da Wang Dr. Christian Richter Andreas Rühling Dr. Patrick Drücker Daniel Siegmund Prof. Dr. Nils Metzler‐Nolte Prof. Dr. Frank Glorius Prof. Dr. Hans‐Joachim Galla 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15123-15126
A series of imidazolium salts bearing two alkyl chains in the backbone of the imidazolium core were synthesized, resembling the structure of lipids. Their antibacterial activity and cytotoxicity were evaluated using Gram‐positive and Gram‐negative bacteria and eukaryotic cell lines including tumor cells. It is shown that the length of alkyl chains in the backbone is vital for the antibiofilm activities of these lipid‐mimicking components. In addition to their biological activity, their surface activity and their membrane interactions are shown by film balance and quartz crystal microbalance (QCM) measurements. The structure–activity relationship indicates that the distinctive chemical structure contributes considerably to the biological activities of this novel class of lipids. 相似文献
9.
Two approaches for the total synthesis of (+)-sapinofuranone B have been described. The first strategy utilizes the methodology developed earlier in our group to get the chiral propargyl alcohol and the second strategy involves generation of threo-1,2-diol derivative by diastereoselective and enantioselective addition of [(Z)-γ-methoxymethoxyallyl]diisopinocampheylborane onto aldehyde and cross metathesis as the key steps. 相似文献
10.