نتایج جستجو برای: electronic rearrangement
تعداد نتایج: 252431 فیلتر نتایج به سال:
Rearrangement reactions of cycloalkenyl phenol and naphthyl ethers and the acid-catalyzed cyclization of the resulting product were investigated. Claisen rearrangement afforded 2-substituted phenol and naphthol derivatives. Combined Claisen and Cope rearrangement resulted in the formation of 4-substituted phenol and naphthol derivatives. In the case of cycloocthylphenyl ether the consecutive Cl...
Electronic spectra are reported for two ring-substituted benzyl-like radicals, 3-picolyl and 2, 5-lutidyl. These pyridine-based radicals have much shorter excited state (D1) lifetimes than their benzyl radical prototypes. The 3-picolyl radical (3-(ĊH2)C5H4N) has an excited-state D1 lifetime of ∼9 ns, and the 2,5-lutidyl radical (2-(CH3),5-(ĊH2)C5H3N) has an excited-state D1 lifetime of ∼245 ns....
A theoretical investigation (AIM and ELF analyses together with NMR chemical shifts) has been conducted for three-membered heterocycle (N, P, and As) oxides. An aromatic stabilization was found for the P and As rings. However, the N derivatives displayed a net negative hyperconjugation in the N-O bond formation, without ring aromaticity observed for their electronic properties. The calculated d...
Fluoroquinolones (FQs) constitute an important class of biologically active broad-spectrum antibacterial drugs that are which are in contact with many biological fluids under different acidity conditions. We studied the reactivity of ciprofloxacin (Cpx) and levofloxacin (Lev) and their interaction with lysozyme (Lyz) at different pH values, using UV-visible absorption, fluorescence, infrared sp...
Botrytis cinerea is a polyphagous fungal parasite which causes serious damage to more than 200 plant species and consequent economic losses for commercial crops. This pathogen produces two families of phytotoxins, the botryanes and botcinins, which are involved in the infection mechanism. The B. cinerea genome has provided a complete picture of the genes involved in the biosynthesis of its seco...
we prove the existence of steady 2-dimensional flows, containing a bounded vortex, and approaching a uniform flow at infinity. the data prescribed is the rearrangement class of the vorticity field. the corresponding stream function satisfies a semilinear elliptic partial differential equation. the result is proved by maximizing the kinetic energy over all flows whose vorticity fields are rearra...
The base-induced Sommelet-Hauser rearrangement of N-α-branched benzylic azetidine-2-carboxylic acid ester-derived ammonium salts to obtain α-arylazetidine-2-carboxylic acid esters was investigated. The substrates, two diastereomeric salts (1S,2S,1'S)- and (1R,2R,1'S)-2, showed different reactivities. The rearrangement of (1S,2S,1'S)-2a proceeded with a perfect N-to-C chirality transfer to provi...
We use Density Functional Theory (DFT) and structure searching methods to show that the ground state of elemental sulfur is a Barium-IVa type incommensurate host-guest (HG) phase between $386$-$679$ GPa, becoming first group-VI element predicted possess such structure. Within HG phase, undergoes series transitions in which adjacent guest chains are not aligned but rather offset by different amo...
We present the ?3-coordination of 2-phosphaethynthiolate anion in complex (PN)2La(SCP) (2) [PN=N-(2-(diisopropylphosphanyl)-4-methylphenyl)-2,4,6-trimethylanilide)]. Structural comparison with dinuclear thiocyanate-bridged (PN)2La(?-1,3-SCN)2La(PN)2 (3) and azide-bridged (PN)2La(?-1,3-N3)2La(PN)2 (4) complexes indicates that [SCP]? coordination mode is mainly governed by electronic, rather than...
uterine leiomyomas/fibroids are the most common pelvic tumors of the female genital tract. the initiators remaining unknown, estrogens and progesterone are considered as promoters of fibroid growth. fibroids are monoclonal tumors showing 40-50% karyo-typically detectable chromosomal abnormalities. cytogenetic aberrations involving chromosomes 6, 7, 12 and 14 constitute the major chromosome abno...
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