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131.
A dual-catalysis approach, namely the combination of an achiral nucleophilic catalyst and a chiral anion-binding catalyst, was applied to the Steglich rearrangement to provide α,α-disubstituted amino acid derivatives in a highly enantioselective fashion. Replacement of the nucleophilic co-catalyst for isoquinoline resulted in a divergent reaction pathway and an unprecedented transformation of O-acylated azlactones. This strategy provided highly substituted α,β-diamino acid derivatives with excellent levels of stereocontrol. 相似文献
132.
The present preliminary investigation reports, for the first time, the effects of typical cationic and anionic surfactants
on the microwave-assisted solid-state intercalation and polymerization of carbazole (Cz) in the basal spacings of Bentonite.
The intercalation of cetyl pyridinium chloride (CPCl), a cationic surfactant, and naphthalene sulfonic acid (NSA), an anionic
surfactant, in Bentonite was carried out at two loadings—25 and 50 wt%—using microwave irradiation. The in situ polymerization
of Cz was successfully carried out into the surfactant-modified galleries of Bentonite. This was confirmed by Gel permeation
chromatography (GPC). The intercalation of poly(carbazole) (PCz) was confirmed by FT-IR, UV–Visible, and XRD analyses. Although
polymerization was carried out in the solid-state, the UV–Visible spectra revealed the doped state of PCz and the presence
of a charge carrier tail. The XRD studies showed that the increase in the height of the galleries was higher in case of Bentonite/CPCl/PCz
nanocomposites as compared to Bentonite/NSA/PCz nanocomposites. It also revealed different orientations of the two surfactants
in the galleries of the clay. The average particle size of Bentonite/CPCl/PCz (1:0.25:0.25) and (1:0.5:0.5) nanocomposites
was found to be in the range of 25–35 and 50–60 nm, respectively. The Bentonite/NSA/PCz (1:0.25:0.25) and (1:0.5:0.5) nanocomposites
showed the average particle size in the range of 20–30 nm and 40–50 nm, respectively. The results revealed that both cationic
and anionic surfactants strongly influenced the morphology of Bentonite/PCz nanocomposites. The difference in the mechanisms
of solid-state intercalation of PCz in the presence of these surfactants has been proposed. 相似文献
133.
Basak P Nisha CK Manorama SV Maiti S Jayachandran KN 《Journal of colloid and interface science》2003,262(2):560-565
The effect of salt on the associative behavior of intramolecular aggregates obtained from poly(ethylene glycol)-based amphiphilic comb-like polymers in aqueous medium at pH 6.2 has been investigated by surface tension, fluorescence probe, dynamic light-scattering, and viscometry techniques. Results reveal that the addition of salt screens the electrostatic repulsion between the charges along the polymer backbone in the aggregates and consequently (1) reduces the surface activity at the air/water interface, (2) leads to the contraction of the polymer backbone, and (3) reduces the hydrodynamic sizes of the aggregates. In contrast, the hydrophobicity of the aggregates remains unperturbed. 相似文献
134.
A laboratory study was carried out by electrochemical oxidation to destroy cyanide in aqueous waste. The electrode used in this study was a triple oxide coated titanium based mesh type anode and a carbon cathode. Direct and indirect methods were both carried out at alkaline conditions and indirect oxidation method in the presence of chloride was found to be more efficient. 相似文献
135.
Palladium‐Catalyzed Synthesis of Phenanthridine/Benzoxazine‐Fused Quinazolinones by Intramolecular CH Bond Activation 下载免费PDF全文
Puneet K. Gupta Nisha Yadav Subodh Jaiswal Mohd. Asad Dr. Ruchir Kant Dr. Kanchan Hajela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13210-13215
A highly efficient synthesis of phenanthridine/benzoxazine‐fused quinazolinones by ligand‐free palladium‐catalyzed intramolecular C?H bond activation under mild conditions has been developed. The C?C coupling provides the corresponding N‐fused polycyclic heterocycles in good to excellent yields and with wide functional group tolerance. 相似文献
136.
Numerical Algorithms - For a nonlinear nonlocal parabolic problem containing the elastic energy coefficients, an expanded mixed finite element method using lowest order RT spaces is discussed in... 相似文献
137.
Selvam Athavan Alias Anand Kiran George Nisha Susan Thomas 《Phosphorus, sulfur, and silicon and the related elements》2020,195(10):821-829
AbstractTwo series of thiazinone and thiosemicarbazone derivatives (1-12) were synthesized using 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-ones (ABNs) and 3–alkyl–2,6–diarylpiperidin–4–ones as the starting materials. The structures of newly synthesized compounds were established on the basis of FT–IR, NMR spectroscopy and mass spectrometry. From the spectroscopic data, we identified that the cyclization reaction of thioamide with dialkyl acetylenedicarboxylate selectively gives six membered methyl 2-(2-(2,4-disubstituted-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazinyl)-4-oxo-4H-1,3-thiazine-6-carboxylates (1-6). In order to investigate the antitumor activities of the synthesized compounds, in vitro cytotoxicity studies were carried out using human prostate cancer cell lines. Tested compounds showed good/moderate activities against cancer cell lines and further investigation carried out by live/dead assay. 相似文献