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21.
J.S. Yadav B.V. Subba Reddy D. Narasimha Chary D. Chandrakanth 《Tetrahedron letters》2009,50(10):1136-6353
A variety of alkenes are converted into the corresponding α-fluoroamides in high yields by selectfluorTM in the presence of 10 mol % of InF3 in nitrile solution. α-Bromoamides are obtained with NBS in the presence of 10 mol % InBr3 under similar conditions. The use of Lewis acid in haloamidation significantly improved the yields and reaction rates. 相似文献
22.
V. Naresh Chary Ch. Dinesh Kumar M. Vairamani S. Prabhakar 《Journal of mass spectrometry : JMS》2012,47(1):79-88
Betaines belong to the naturally occurring osmoprotectants or compatible solutes present in a variety of plants, animals and microorganisms. In recent years, metabolomic techniques have been emerging as a fundamental tool for biologists because the constellation of these molecules and their relative proportions provide with information about the actual biochemical condition of a biological system. Therefore, identification and characterization of biologically important betaines are crucial, especially for metabolomic studies. Most of the natural betaines are derived from amino acids and related homologues. Although, theoretically, all the amino acids can be converted to corresponding betaines by simple methylation of the amine group, only a few of the amino acid‐derived betaines were fully characterized in the literature. Here, we report a combined electrospray ionization tandem and high‐resolution mass spectrometry study of all the betaines derived from amino acids, including the isomeric betaines. The decomposition pathway of protonated, sodiated and potassiated molecule ions that enable unambiguous characterization of the betaines including the isomeric betaines and overlapping ionic species of different betaines is distinctive. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
23.
Mohan G. Sridhar G. Laxminarayana E. Chary M. T. 《Russian Journal of Organic Chemistry》2021,57(9):1495-1500
Russian Journal of Organic Chemistry - A series of N-[2-(4-methoxyanilino)-5-(3,4,5-trimethoxyphenyl)pyridin-3-yl]benzamides have been synthesized, and their structure was confirmed by 1H and 13C... 相似文献
24.
Chidrawar Ajay Devulapally Yogananda Chary Dr. Sridhar Balasubramanian Dr. Basi V. Subba Reddy 《European journal of organic chemistry》2023,26(13):e202201361
Rh(III)-catalyzed C−H bond annulation of 2-arylquinoxalines with cyclic 2-diazo-1,3-diketones has been accomplished for the first time to synthesize a novel series of 2,3-dihydrodibenzo[a,c]phenazin-4(1H)-one frameworks by means of carbene insertion followed by condensation. The reaction proceeds through the C−H bond activation and functionalization of 2-arylquinoxalines using Rh(III)/AgSbF6 complex to produce highly substituted 2,3-dihydrodibenzo[a,c]phenazin-4(1H)-one and benzo[5,6][1,2,4]thiadiazino[2,3-f]phenanthridin-5(6H)-one-10,10-dioxide derivatives in good to excellent yields. 相似文献
25.
Use of partial or selective (13)C/(15)N labeling of specific amino acid residues in a given protein to measure the values of (1)J((15)N(i),(13)C(alpha) (i)), (2)J((1)H(N),(13)C(alpha) (i)), (2)J((15)N(i),(13)C(alpha) (i-1)), (1)J((15)N(i),(13)C'(i-1)) and (2)J((1)H(N),(13)C'(i-1)) is described. This was achieved by recording a sensitivity-enhanced 2D [(15)N-(1)H] HSQC experiment, without mixing the spin states of C(alpha) and C' during the course of entire experiment. 相似文献
26.
The synthesis of 3'-deoxycapsanthin (1) and 3,4-didehydroxy-3'-deoxycapsanthin (2), carotenoids of paprika, has been achieved by employing Lewis acid-promoted regio- and stereoselective rearrangement of the C(15)-epoxy dienal 5a. The absolute stereochemistry of the newly formed C-5 chiral center of rearrangement product 6a was determined to be (R) from its alternative synthesis derived from (+)-(R)-camphonanic acid (11). 相似文献
27.
The design, fabrication, and testing of photoelastic models of double-lap, multiple-pin connectors are discussed. Interest
is in the stresses in the inner laps. These stresses are determined by constructing models with photoelastic inner laps and
transparent-acrylic outer laps. The connectors have two pins, in tandem, parallel to the load direction. A photoelastic-isotropic
point is shown to permit the evaluation of load sharing between the two pins. A numerical scheme, utilizing the isochromatic-
and isoclinic-photoelastic data and a finite-difference representation of the planestress equilibrium equations, is used to
compute the stresses around the two pins. Representative stress distributions and stress-concentration factors are shown. 相似文献
28.
Pavankumar Pallerla Sudarshana Reddy Bhumireddy Sai Sachin Lingampally Nagarjuna Chary Ragi Prabhakar Sripadi 《Journal of mass spectrometry : JMS》2019,54(9):761-771
Methylation is one of the important posttranslational modifications of biological systems. At the metabolite level, the methylation process is expected to convert bioactive compounds such as amino acids, fatty acids, lipids, sugars, and other organic acids into their methylated forms. A few of the methylated amino acids are identified and have been proved as potential biomarkers for several metabolic disorders by using mass spectrometry–based metabolomics workstation. As it is possible to encounter all the N‐methyl forms of the proteinogenic amino acids in plant/biological systems, it is essential to have analytical data of all N‐methyl amino acids for their detection and identification. In earlier studies, we have reported the ESI‐MS/MS data of all methylated proteinogenic amino acids, except that of mono‐N‐methyl amino acids. In this study, the N‐methyl amino acids of all the amino acids ( 1 ‐ 21 ; including one isomeric pair) were synthesized and characterized by ESI‐MS/MS, LC/MS/MS, and HRMS. These data could be useful for detection and identification of N‐methyl amino acids in biological systems for future metabolomics studies. The MS/MS spectra of [M + H]+ ions of most N‐methyl amino acids showed respective immonium ions by the loss of (H2O, CO). The other most common product ions detected were [MH‐(NH2CH3]+, [MH‐(RH)]+ (where R = side chain group) ions, and the selective structure indicative product ions due to side chain and N‐methyl group. The isomeric/isobaric N‐methyl amino acids could easily be differentiated by their distinct MS/MS spectra. Further, the MS/MS of immonium ions inferred side chain structure and methyl group on α‐nitrogen of the N‐methyl amino acids. 相似文献
29.
ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献
30.
Chary NS Herrera S Gómez MJ Fernández-Alba AR 《Analytical and bioanalytical chemistry》2012,404(6-7):1993-2006
A new analytical method using stir-bar-sorptive extraction (SBSE) followed by liquid desorption (LD) and gas chromatography with triple-quadrupole mass spectrometric detection (GC-QqQ-MS-MS) has been used for quantitative determination of 25 chlorinated endocrine-disrupting compounds (EDCs) in river water and wastewater. The experimental conditions affecting the SBSE-LD performance were studied and are discussed in detail. Results from systematic assay revealed that a 100-mL water sample, stir bars coated with 47?μL PDMS, an extraction time of 14?h (at 900?rpm), 5?% MeOH as modifier and 10?% NaCl resulted in the best analytical recovery of all the target compounds studied. Use of 1:1 ACN-MeOH as back-extraction solvent and two successive sonication steps, each for 5?min, resulted in the best performance for monitoring EDCs in water matrices. The method detection limits for most of the target compounds were very good- ≤?2?ng?L(-1) and ≤10?ng?L(-1) for river water and wastewater effluents respectively. Experimental recovery for all the compounds was >70?%, with the exception of simazine for which recovery from the matrix was 65?%. Signal enhancement observed for a few of the compounds in wastewater effluents was managed by use of matrix-matched standards and different injection liners. The method was successfully used for analysis of river water samples from Henares River (Spain) and wastewater effluent samples from wastewater-treatment plants (WWTP). Eleven of the 25 compounds studied were detected in both river water and wastewater effluents. Terbutylazine and methoxychlor were detected in almost all the river water and effluent samples; amounts varied between 37-58.5?ng?L(-1) and 15.2-46.8?ng?L(-1), respectively. This method was shown enable reliable, effective, and sensitive monitoring of chlorinated EDCs at nanogram levels in surface water and wastewater effluent. 相似文献