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11.
Jackson P Srinivas R Blanksby SJ Schroder D Schwarz H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1236-1242
The cation [Si,C,O]+ has been generated by 1) the electron ionisation (EI) of tetramethoxysilane and 2) chemical ionisation (CI) of a mixture of silane and carbon monoxide. Collisional activation (CA) experiments performed for mass-selected [Si,C,O]+, generated by using both methods, indicate that the structure is not inserted OSiC+; however, a definitive structural assignment as Si(+)-CO, Si(+)-OC or some cyclic variant is impossible based on these results alone. Neutralisation-reionisation (+NR+) experiments for EI-generated [Si,C,O]+ reveal a small peak corresponding to SiC+, but no detectable SiO+ signal, and thus establishes the existence of the Si(+)-CO isomer. CCSD(T)@B3LYP calculations employing a triple-zeta basis set have been used to explore the doublet and quartet potential-energy surfaces of the cation, as well as some important neutral states. The results suggest that both Si(+)-CO and Si(+)-OC isomers are feasible; however, the global minimum is 2 pi SiCO+. Isomeric 2 pi SiOC+ is 12.1 kcal mol-1 less stable than 2 pi SiCO+, and all quartet isomers are much higher in energy. The corresponding neutrals Si-CO and Si-OC are also feasible, but the lowest energy Si-OC isomer (3A") is bound by only 1.5 kcal mol-1. We attribute most, if not all, of the recovery signal in the +NR+ experiment to SiCO+ survivor ions. The nature of the bonding in the lowest energy isomers of Si(+)-(CO,OC) is interpreted with the aid of natural bond order analyses, and the ground state bonding of SiCO+ is discussed in relation to classical analogues such as metal carbonyls and ketenes. 相似文献
12.
The ene reaction of sulfur dioxide with enoxysilanes or with allylsilanes generates silyl sulfinates that can be brominated (Br(2) or NBS) or chlorinated (NCS or Cl(2)) to produce the corresponding sulfonyl halides. They react with primary and secondary amines or alcohols to give the corresponding sulfonamides and sulfonic esters, respectively. The hetero-Diels-Alder addition of sulfur dioxide to 1-oxy- or 1,3-dioxy-1,3-dienes generates zwitterions that add to enoxysilanes or allylsilanes giving silyl sulfinates that can be converted in situ into polyfunctional sulfonamides or sulfonic esters. This realizes quick access to libraries of complicated sulfonamides and sulfonic esters applying one-pot, three- and four-component methods. 相似文献
13.
Transition-metal-catalyzed carbon-carbon bond-forming reactions are among the most powerful methods in organic synthesis and play a crucial role in modern materials science and medicinal chemistry. Recent developments in the area of ligands and additives permit the cross-coupling of a large variety of reactants, including inexpensive and readily available sulfonyl chlorides. Their desulfitative carbon-carbon cross-coupling reactions (Negishi, Stille, carbonylative Stille, Suzuki-Miyaura, and Sonogashira-Hagihara-type cross-couplings and Mizoroki-Heck-type arylations) are reviewed together with carbon-carbon cross-coupling reactions with other organosulfur compounds as electrophilic reagents. 相似文献
14.
Gantasala N. Srinivas 《Journal of organometallic chemistry》2006,691(11):2503-2511
η2 π-Complexes of Ge2H2 with the organometallic fragments V(PH3)2(I)(CO)2, Cr(CO)4, Co(PH3)2(Cl) and M(PH3)2 (M = Ni, Pd, Pt) have been studied at the B3LYP level using the SBKJC relativistic effective core potentials and their associated basis sets on metals and iodine, and the 6-31G(d) basis set on all other elements. The transition metal fragments of V, Cr, Co, Ni, Pd and Pt were chosen based on known alkyne compounds. All the complexes are local minima for both the HGeGeH and GeGeH2 isomers of the Ge2H2 ligand. The complexes containing GeGeH2 isomer as a ligand are lower in energy than those with the HGeGeH ligand (except in the V complex in which the difference is only 1.0 kcal/mol). There is a net charge transfer from ligand to metal in complexes V-Co and from metal to ligand in late transition metal complexes (Ni-Pt). 相似文献
15.
Yao M Mantha S Shah VR Vachharajani NN Arnold ME Pursley JM Srinivas NR 《Biomedical chromatography : BMC》2002,16(3):175-182
A high performance liquid chromatographic-mass spectrometric (LC/MS) assay was developed and validated for the determination of BMS-204352 in dog K(3)EDTA plasma. A 0.5 mL aliquot of control plasma was spiked with BMS-204352 and internal standard (IS) and buffered with 1 mL of 5 mM ammonium acetate. The mixture was then extracted with 3 mL of toluene. After separation and evaporation of the organic phase to dryness using nitrogen at 40 degrees C, the residue was reconstituted in the mobile phase and 25 microL of the sample were injected onto a Hypersil C(18) column (2 x 50 mm; 3 microm) at a flow rate of 0.5 mL/min. The mobile phase was consisted of two solvent mixtures (A and B). Solvent A was composed of 5 mM ammonium acetate and 0.1% triethylamine in 75:25 v/v water:methanol, pH adjusted to 5.5 with glacial acetic acid, and solvent B was 5 mM ammonium acetate in methanol. A linear gradient system was used to elute the analytes. The mass spectrometer was programmed to admit the de-protonated molecules at m/z 352.7 (IS) and m/z 357.9 (BMS-204352). Standard curves of BMS-204352 were linear (r(2) > or = 0.998) over the concentration range of 0.5-1000 ng/mL. The mean predicted quality control (QC) concentrations deviated less than 5.1% from the corresponding nominal values (ie 4, 80, 400 and 2000 ng/mL); the within- and between-assay precision of the assay were within 5.5% relative standard deviation. Stability of BMS-204352 was confirmed after at least three freeze/thaw cycles and BMS-204532 was stable in dog plasma when stored frozen at or below -20 degrees C for at least 16 weeks in spiked QC samples and for at least 4 1/2 weeks for in vivo study samples. BMS-204352 and IS were stable in the injection solvent at room temperature for at least 24 h. The assay was applied to delineate the pharmacokinetic disposition of BMS-204352 in dogs following a single intravenous dose administration. In conclusion, the assay is accurate, precise, specific, sensitive and reproducible for the pharmacokinetic analysis of BMS-204532 in dog plasma. 相似文献
16.
Korupoju SR Mangayarkarasi N Zacharias PS Mizuthani J Nishihara H 《Inorganic chemistry》2002,41(16):4099-4101
New homo trinuclear Zn(II) complexes [Zn(3)L(1)(micro-OAc)](ClO(4))(2).3CHCl(3).H(2)O, 1, and [Zn(3)L(1)(micro-OAc)].ClO(4).PF(6).5CH(3)OH.H(2)O, 2, and hetero trinuclear complex [Zn(2)CuL(1)(micro-OAc)](ClO(4))(2).3CHCl(3).H(2)O,3, of optically active hexaaza triphenolic macrocycle H(3)L(1) were synthesized and crystallographically characterized. The cation [Zn(3)L(1)(micro-OAc)](+) structure of 1 and 2 closely resembles the trinuclear Zn(II) active site of P1 nuclease. The distorted tetrahedral geometry of Zn3 was successfully reproduced at Cu1 in complex 3. The complexes 2 and 3 cleave CT DNA at 37 and 50 degrees C. 相似文献
17.
Nirmal Kumar S. Appari Srinivas Kuncharam Bhanu Vardhan Reddy 《Catalysis Surveys from Asia》2021,25(4):362-388
Catalysis Surveys from Asia - Sulfur poisoning of catalyst is a well-known phenomenon observed during the production of syngas (CO?+?H2). The presence of traces of sulfur... 相似文献
18.
The addition of sulfur and silver to Rh/SiO2 inhibits hydrogenation of C2H4, but promotes CO insertion and extends the linearity of Arrhenius curves for CO insertion above 543 K.
Rh/SiO2 C2H4, CO CO 543 .相似文献
19.
Yakaiah Chinthala Manjulatha K Pooja Sharma Satya Srinivas Kvn Kotesh Jonnala Niranjana Kumar Arigari Feroz Khan Setty Oh 《Journal of heterocyclic chemistry》2016,53(6):1902-1910
A series of new andrographolide‐1,2,3‐triazole derivatives, 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , were synthesized from a natural bioactive labdane type diterpenoid, andrographolide. All the derivatives were screened against human cancer cell lines MCF7, MDA‐MB‐231, COLO205, HepG2, K562, Hela, and HEK293 to evaluate their cytotoxic activity. All the compounds showed anticancer activity selectively against K562 cell line, with IC50 values ranging from 8.00 to 17.11 µM, and are inactive against the rest of the cell lines. Compounds 3c and 3d showed significant cytotoxicity among the synthesized derivatives. The in silico docking studies revealed compounds 3b and 3d with high binding affinity against the cancer target, transient receptor potential vanilloid 1. 相似文献
20.
Roshan M. Borkar Murali Mohan Bhandi Ajay P. Dubey V. Ganga Reddy Prashanth Komirishetty Prajwal P. Nandekar Abhay T. Sangamwar Ahmed Kamal Sanjay K. Banerjee R. Srinivas 《Biomedical chromatography : BMC》2016,30(10):1556-1572
The aim of the present study was to evaluate the contribution of metabolites to drug–drug interaction and drug–herb interaction using the inhibition of CYP2D6 and CYP3A4 by metoprolol (MET) and its metabolites. The peak concentrations of unbound plasma concentration of MET, α‐hydroxy metoprolol (HM), O‐desmethyl metoprolol (ODM) and N‐desisopropyl metoprolol (DIM) were 90.37 ± 2.69, 33.32 ± 1.92, 16.93 ± 1.70 and 7.96 ± 0.94 ng/mL, respectively. The metabolites identified, HM and ODM, had a ratio of metabolic area under the concentration–time curve (AUC) to parent AUC of ≥0.25 when either total or unbound concentration of metabolite was considered. In vitro CYP2D6 and CYP3A4 inhibition by MET, HM and ODM study revealed that MET, HM and ODM were not inhibitors of CYP3A4‐catalyzed midazolam metabolism and CYP2D6‐catalyzed dextromethorphan metabolism. However, DIM only met the criteria of >10% of the total drug related material and <25% of the parent using unbound concentrations. If CYP inhibition testing is solely based on metabolite exposure, DIM metabolite would probably not be considered. However, the present study has demonstrated that DIM contributes significantly to in vitro drug–drug interaction. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献