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排序方式: 共有166条查询结果,搜索用时 234 毫秒
1.
J.S. Yadav B.V. Subba Reddy K.V. Raghavendra Rao G.G.K.S. Narayana Kumar 《Tetrahedron letters》2007,48(31):5573-5576
Indoles undergo smooth alkylation with propargylic alcohols in the presence of 10 mol % of scandium triflate under mild conditions to produce 3-propargylated indoles in excellent yields with high selectivity. 相似文献
2.
LetX be a compact Riemann surface andM s p (X) the moduli space of stable parabolic vector bundles with fixed rank, degree, rational weights and multiplicities. There is a natural Kähler metric onM s p (X). We obtain a natural metrized holomorphic line bundle onM s p (X) whose Chern form equalsmr times the Kähler form, wherem is the common denominator of the weights andr the rank. 相似文献
3.
Aishakhanam H. Pathan Ganesh N. Naik Raghavendra P. Bakale Shrinath S. Machakanur Kalagouda B. Gudasi 《应用有机金属化学》2012,26(3):148-155
A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of a tridentate hydrazone were prepared and characterized by various spectro‐analytical techniques and magnetic moment studies. The complexes were found to be monomeric and non‐electrolytes. The copper complex is electrochemically active in the applied potential range. The compounds synthesized in the present study have shown promising antiproliferative activity when screened using the in vitro method against two human cancer cell lines: HeLa and HepG2. The Escherichia coli DNA‐binding properties of all the compounds were investigated with UV–visible absorption spectrophotometric titrations, viscosity measurements, DNA melting experiments and gel electrophoreses measurements. The compounds were demonstrated to act as DNA intercalators with appreciable DNA‐binding constant values. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
H. R. Prakash Naik H. S. Bhojya Naik T. R. Ravikumar Naik M. Raghavendra T. Aravinda D. S. Lamani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):460-470
The synthesis of quinoline-substituted phenylquinazolinones containing sulfur and selenium is described. These molecules were isolated from a series of reactions of 2-phenyl-4H-3,1-benzoxazin-4-one with 2-chloro, 2-thieno, and 2-selenoquinoline-3-carbaldehyde hydrazones. The structure of the isolated compounds has been elucidated on the basis of IR, 1 H NMR, mass spectral, and elemental analysis data. 相似文献
5.
Chigalli N. Revanna Goravanahalli M. Raghavendra Kebbahalli N. Nandeesh Doddamedur G. Bhadregowda Kanchugarakoppal S. Rangappa Kempegowda Mantelingu 《Tetrahedron letters》2013
5-Allyl-7,7-difluoro-2-(2,4-difluorophenyl)-6-(4-methoxyphenyl)-4,5,6,7-tetrahydro-2H-pyrazolo[4,3-c]pyridine-3-amine represents a fluorinated heterocyclic scaffold, potentially attractive. It was synthesized via Michael addition, Mannich reaction of the difluorinated ethyl bromoacetate with a benzotriazole derivative, followed by a Dieckmann condensation. Starting from simple materials, this efficient route which gives access to novel functionalized N-(5-allyl-7,7-dihalo)-4,5,6,7-tetrahydro-2H-indazol-3-yl)-carboxymides, was explored and adapted for parallel synthesis, resulting in a compound library. 相似文献
6.
K. Raghavendra Rao Akula Raghunadh Ramamohan Mekala Suresh Babu Meruva T.V. Pratap T. Krishna Dipak Kalita Eppakayala Laxminarayana Bagineni Prasad Manojit Pal 《Tetrahedron letters》2014
A dual reactant/catalyst role of glyoxylic acid in the reaction of isatoic anhydride with various amines afforded a novel, robust and rapid synthesis of 3-(un)substituted quinazolin-4(3H)-ones. This metal catalyst-free reaction proceeds via an unusual and unexpected cleavage of C–C bond. A shorter and common route to two alkaloids, that is, rutaecarpine and evodiamine is also accomplished. 相似文献
7.
Ranjit Bag Sourav Kar Suvam Saha Suman Gomosta Beesam Raghavendra Thierry Roisnel Sundargopal Ghosh 《化学:亚洲杂志》2020,15(6):780-786
Triply‐bridging bis‐{hydrido(borylene)} and bis‐borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe2(CO)9] with an in situ produced intermediate, generated from the low‐temperature reaction of [Cp*WCl4] (Cp*=η5‐C5Me5) and [LiBH4?THF] afforded triply‐bridging bis‐{hydrido(borylene)}, [(μ3‐BH)2H2{Cp*W(CO)2}2{Fe(CO)2}] ( 1 ) and bis‐borylene, [(μ3‐BH)2{Cp*W(CO)2}2{Fe(CO)3}] ( 2 ). The chemical bonding analyses of 1 show that the B?H interactions in bis‐{hydrido (borylene)} species is stronger as compared to the M?H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO‐LUMO for 2 as compared to 1 . In an attempt to synthesize the ruthenium analogue of 1 , a similar reaction has been performed with [Ru3(CO)12]. Although we failed to get the bis‐{hydrido(borylene)} species, the reaction afforded triply‐bridging bis‐borylene species [(μ3‐BH)2{WCp*(CO)2}2{Ru(CO)3}] ( 2′ ), an analogue of 2 . In search for the isolation of bridging bis‐borylene species of Rh, we have treated [Co2(CO)8] with nido‐[(RhCp*)2(B3H7)], which afforded triply‐bridging bis‐borylene species [(μ3‐BH)2(RhCp*)2Co2(CO)4(μ‐CO)] ( 3 ). All the compounds have been characterized by means of single‐crystal X‐ray diffraction study; 1H, 11B, 13C NMR spectroscopy; IR spectroscopy and mass spectrometry. 相似文献
8.
Eltayib Hassan Ahmed Tripti Raghavendra Datta Madamwar 《Applied biochemistry and biotechnology》2010,160(7):2102-2113
A mesophilic bacterial culture producing a novel thermostable alkaline lipase was isolated from oil rich soil sample and identified
as Bacillus subtilis EH 37. The lipase was partially purified by ammonium sulfate precipitation and hydrophobic interaction chromatography with
17.8-fold purification and 41.9 U/ml specific activity. The partially purified enzyme exhibited maximum activity at pH 8.0
and at 60 °C. It retained 100% of activity at 50 °C and 60 °C for 60 min. The presence of Ca+2, Mg+2, and Zn2+ exhibited stimulatory effect on lipase activity, whereas Fe+3 and Co+2 reduced its activity. The enzyme retained more than 80% of its initial activity upon exposure to organic solvents, exhibited
107% and 115% activity in the presence of 15% isopropyl alcohol and 30% n-hexane, respectively. The EH 37 lipase also proved
to be an efficient catalyst in synthesis of ethyl caprylate in organic solvent, thus providing a concept of application of
B. subtilis lipase in non-aqueous catalysis. 相似文献
9.
Murugan R Mallavarapu GR Padmashree KV Rao RR Livingstone C 《Natural product communications》2010,5(12):1961-1964
The volatile oil of the leaves of Pogostemon heyneanus Benth. (Lamiaceae) was analyzed by GC and GC-MS. Twenty-six components representing 96.0% of the oil were identified. The major components of the oil were acetophenone (51.0%), beta-pinene (5.3%), (E)-nerolidol (5.4%), and patchouli alcohol (14.0%). Comparison of the compositions of the oils of P. heyneanus and P. cablin (Blanco) Benth. (Patchouli oil) showed wide variation between them. Though 13 sesquiterpenes and oxygenated sesquiterpenes were detected in both oils, their concentrations in the oils differed widely. Acetophenone, benzoyl acetone and (E)-nerolidol present in the oil of P. heyneanus were not detected in patchouli oil. 相似文献
10.
T. Raghavendra RaoCh. Rama Krishna U.S. Udayachandran ThampyCh. Venkata Reddy Y.P. ReddyP. Sambasiva Rao R.V.S.S.N. Ravikumar 《Physica B: Condensed Matter》2011,406(11):2132-2137
The effect of Li2O content in vanadyl doped 20ZnO+xLi2O+(30−x)Na2O+50B2O3 (5≤x≥25) glasses has been studied with respect to their physical and structural properties. The absence of sharp peaks in XRD spectra of these glass samples confirms the amorphous nature. The physical parameters like density, refractive index, ionic concentration and electronic polarizability vary non-linearly with x mol% depending on the diffusivities of alkali ions. EPR and optical absorption spectra reveal that the resonance signals are characteristics of VO2+ ions in tetragonally compressed octahedral site. Spin-Hamiltonian, crystal field, tetragonal field and bonding parameters are found to be in good agreement with the other reported glass systems. The tetragonal distortion (g⊥-g∥) and Dt reveals that their values vary non-linearly with Li2O content and reaches a minimum at x=10 mol%. An anomaly of character has been observed in all the properties of vanadyl doped glass systems, which gives a clear indication of mixed alkali effect. 相似文献