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排序方式: 共有128条查询结果,搜索用时 31 毫秒
51.
Nissy Ann Harry Sankaran Radhika Mohan Neetha Gopinathan Anilkumar 《Journal of heterocyclic chemistry》2020,57(4):2037-2043
A rapid, efficient, and green grinding assisted method for the synthesis of 2,3-dihydro-1H-perimidines has been developed. 1,8-Diaminonaphthalene and aldehydes were ground using mortar and pestle for 5 minutes affording the product in moderate to excellent yields. The methodology minimises the use of conventional workup and column chromatographic techniques. 相似文献
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Cyclotides, a class of macrocyclic plant peptides, characterized by a cyclic backbone and three inter-locking disulfide bonds, may be divided into two major structural subfamilies, Möbius and Bracelet, based on the presence or absence of a specific proline residue. The present study describes the suite of cyclotides obtained from Clitoria ternatea, characterized by LC−MS and MS/MS techniques. Notable variations in product ion distributions were observed in cyclotides belonging to different structural subfamilies based on the number and positions of proline residues. For instance, Cter M which is an abundant Möbius cyclotide in this plant containing three proline residues, displayed distinct b- and y- ion characteristics in the MS/MS spectra compared to Cliotide T1, another commonly identified cyclotide but belonging to the Bracelet subfamily having two proline residues. The distinct fragmentation pattern of prototypical cyclotides of each structural subfamily, determined by Xxx-Pro bond fragmentation, was used to rapidly identify and sequence a novel cyclotide ctr pep 30 from this plant. 相似文献
55.
Biaryls with excellent yields can be prepared by the Ullmann-type coupling of aryl halides in the presence of potassium carbonate (as a base) and dimethylformamide (as a solvent), at 140 °C, using a reusable Pd (2.5 wt%)/ZrO2 catalyst. The product yield of 4-iodoanisole coupling is strongly influenced by the catalyst preparation method, solvent, and base. 相似文献
56.
Ramesh AS Christopher JG Radhika R Setty CR Thankamani V 《Natural product research》2012,26(16):1549-1552
Arjunolic acid (AA), a triterpenoid, was isolated from the ethyl acetate and methanol extracts of Terminalia arjuna core wood. The purity of AA was analysed by its melting point, FT-IR and NMR spectroscopy analyses. In?vitro cytotoxicity was assessed using Ehrlich ascites carcinoma (EAC) and Dalton's lymphoma (DAL) cell lines by incubating with different concentrations of AA. The cancer cell death percentage at 100?μg concentrations of AA ranged between 66% and 70% on the DAL and EAC cell lines, respectively. This infers that AA causes considerable membrane damage to cancer cells. 相似文献
57.
Phytochemical investigation of the methanolic extract of the leaves of Andrographis paniculata Nees yielded a minor, new diterpene, 21-nor-3,19-isopropylidine-14-deoxy-ent-labda-8(17),13-dien-16,15-olide (1), together with five known labdane type diterpenes, andrographolide 3, 14-deoxyandrographolide 4, 14-deoxy-12-hydroxyandrographolide 5, 14-deoxy-11,12-dihydroandrographolide 6, neoandrographolide 7, and two acids, cinnamic acid 8, and ferulic acid 9. The chemical structures were established by spectroscopic analyses, including 1D- and 2D-NMR spectroscopic experiments, and on the basis of HR-ESI MS analyses. The methanolic extract of the leaves exhibited moderate antibacterial and antifungal activities at a dose of 200 microg/mL in comparison with the reference standards. 相似文献
58.
Mixed ligand complexes of Zn(II) and Co(II) with cysteine, histidine, cysteinemethylester, and histidinemethylester have been
synthesized and characterized by elemental analysis, conductivity, magnetic susceptibility measurements, and infrared,1H NMR, TGA and FAB mass spectra. In these complexes, histidine, and histidinemethylester act as bidentate ligands involving
amino and imidazole nitrogens in metal coordination. Similarly, cysteine, and cysteinemethylester also act as bidentate ligands
coordinating through thiol sulphur and amino nitrogen. Tetrahedral geometry has been proposed for Zn(II) and Co(II) complexes
based on experimental evidence. 相似文献
59.
Shrikar M. Bhosale Aadil A. Momin Shrikant Kunjir P.R. Rajamohanan Radhika S. Kusurkar 《Tetrahedron letters》2014
During the total synthesis of calothrixin B, various novel and unexpected results were noticed such as cleavage of C–N bond in imine using sodium cyanoborohydride, sodium methoxide as a hydride source for reduction, deformylation in the presence of bromine, and deacylation using ceric ammonium nitrate (CAN). A detailed mechanism has been proposed for the unexpected results and a few of them are generalized. Temperature dependent NMR studies have been carried out for confirmation of the structure of one of the intermediates in the synthetic sequence. 相似文献
60.
Use of a combination of ionic liquids in the presence of aluminium chloride and microwave irradiation was shown to be a very efficient and high-yielding method for the dehydration of aldoximes and also for 1,3-dipolar cycloadditions. Surprisingly, the presence of acrylonitrile rendered an unusual formation of substituted amide. 相似文献