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31.
[reaction: see text] The iminium ions generated in situ by the oxidation of N,N-diisopropyl-N-benzylamine using iodine react with diaryl ketones in the presence of TiCl4/R3N to give the corresponding 3,3-diarylcyclobutanones in moderate to good yields (49-86%). The 3,3-diarylcyclobutanone iminium ions formed in this transformation was reduced in situ with B2H6 to produce the corresponding 3,3-diarylcyclobutylamines (52-79% yields), a class of compounds with potential antidepressant activity. In addition, a series of N,N-dimethyl-3,3-diarylcyclobutylamines were synthesized by the reductive amination of the corresponding 3,3-diarylcyclobutanone derivatives. 相似文献
32.
The level scheme of79Kr has been studied through the79Br(p,n)79Kr reaction at proton energies from 1·7 to 5·0 MeV.γ-ray and internal conversion electron measurements were made using Ge(Li) detectors and a six gap “Orange” electron spectrometer. The level scheme was established by determining the thresholds of variousγ-rays and byγ-γ and n-γ coincidence measurements. New levels at 402, 450, 660, 676, 695, 720, 810, 836, 907 and 1038 keV not observed in earlier radioactivity studies have been established. DefiniteJ π assignments have been made to most of the levels below 800 keV. Many of the low-lying levels are identified as rotational levels based on the (301 ↓) 1/2?, (301 ↑) 3/2? and (431 ↓) 1/2+ Nilsson states. 相似文献
33.
Bharathi Alagar Muthumani Narayanan Anbalagan Krishnamoorthy 《Transition Metal Chemistry》1997,22(6):586-588
The ground- and excited-state reactivities of the [Cr- (en)3]3+ (en=1,2-diaminoethane) and [Cr(NCS)6]3− ions in a polyacrylamide
(PAA) environment are reported. The aquation kinetics of these complexes has been studied to identify the effect of added
PAA with varying molecular weight. Aquation of the complexes in aqueous acid containing PAA yielded the respective substituted
products. The macromolecule in solution was found to decrease significantly the rate of ligand replacement. Similarly, photolysis
of the cationic and anionic complexes in water–PAA mixtures revealed a decrease in aquation quantum yield. Possible explanations
for the decrease in reaction rates and quantum yields are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
34.
[reaction: see text] Design and synthesis of a novel class of dendrons based on an AB(4) monomer are described. These dendrons have been evaluated by using dendritic encapsulation of a redox active core. The electrochemical properties of symmetric ferrocene-cored dendrimers show that significant alterations in redox potential and heterogeneous electron-transfer rate constants could be achieved even at lower generations. 相似文献
35.
Atul N. Jadhav Chidananda Swamy Rumalla Bharathi Avula Ikhlas A. Khan 《Chromatographia》2007,66(9-10):797-800
Naturally occurring 20-hydroxyecdysone is an important anabolic ecdysteroid. A simple thin-layer chromatography method to quantitate 20-hydroxyecdysone in methanolic extract of the whole plant material of Sida rhombifolia L. was developed. This method was successfully applied for quantitative evaluation of dietary supplements. The separation was achieved on glass TLC plates coated with silica gel 60F254, using chloroform: methanol (8:2 v/v) as developing solvent. Densitometric evaluation of 20-hydroxyecdysone was performed at 250 nm in reflectance/absorbance mode. The calibration was in the range of 200–1,000 ng spot?1 and correlation coefficient for the calibration curve was >0.999. In addition, for six different Sida species unique fingerprints were obtained on the HPTLC plate. 相似文献
36.
R. Purushottamudu Pratibha Nuthakki 《Zeitschrift fur Physik C Particles and Fields》1982,14(3):257-261
Current algebra and partially conserved axial-vector current (PCAC) hypothesis are applied to study the proton-antiproton annihilation process \(\bar pp \to K^ + K^ - 4\pi ^0 \) , treating all the emitted pions as soft. While the σ-terms are ignored, the double commutators giving rise to the divergence of axial-vector currents and representing π?π effects are retained. We express the rate for the process in a fully differential form in terms of the chosen variables and normalize it to the differential rate for the corresponding process without the soft pions. Branching ratios obtained after numerical integration of the expressions are given for various centre-of-mass energies and compared with the available experimental data. 相似文献
37.
Bharathi S. Sampath S. Gun J. Rabinovich L. Wu Z. Pankratov I. Lev O. 《Journal of Sol-Gel Science and Technology》1998,13(1-3):241-244
Three types of reagentless glucose biosensor based on composite graphite-ormosil materials are described: (1) a redox modified silicate-graphite electrode doped with glucose oxidase, (2) a methyl silicate-graphite material doped with redox modified glucose oxidase, and (3) a methyl silicate and redox modified graphite composite material doped with glucose oxidase. 相似文献
38.
39.
[see reaction]. Design and synthesis of a novel class of monodendrons, in which the functional units can potentially be directed toward the concave interiors of dendrimers, are described. The key feature of the design is the placement of the amphiphilic and the AB2 functional groups in orthogonal planes. 相似文献
40.
Bharathi Avula Yan‐Hong Wang Rita M. Moraes Ikhlas A. Khan 《Biomedical chromatography : BMC》2011,25(11):1230-1236
A new rapid UPLC‐UV‐MS method has been developed that permits the analysis of four lignans (4′‐O‐demethylpodophyllotoxin, podophyllotoxin, α‐peltatin and β‐peltatin) in P. peltatum L. Podophyllotoxin is a natural lignan that is being used as a precursor for the semi‐synthetic anti‐cancer drugs etoposide, teniposide and etopophos. The chromatographic separation was achieved using a reversed‐phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. Analyses of P. peltatum leaves collected from different colonies within a single site indicated a significant variation in 4′‐O‐demethylpodophyllotoxin, α‐peltatin, podophyllotoxin and β‐peltatin content. Within 3.0 min four main lignans could be separated with detection limits of 0.1, 0.3, 0.3 and 0.2 μg/mL, respectively. 4′‐O‐demethylpodophyllotoxin and α‐peltatin appeared most prominently among the lignans obtained. The podophyllotoxin content was found in the range of 0.004–0.77% from 16 samples collected from 6 colonies within the same site. The content of podophyllotoxin is directly proportional to the content of 4′‐O‐demethylpodophyllotoxin and inversely proportional to α‐peltatin and β‐peltatin content. LC‐mass spectrometry coupled with electrospray ionization (ESI) interface method is described for the identification of four lignans in various populations of plant samples. By applying principal component analysis and hierarchical cluster analysis, Podophyllum samples collected from various colonies within a location were distinguished. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献