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61.
Emmadi Narender Reddy Atmakur Krishnaiah Tadikamalla Prabhakar Rao 《Tetrahedron: Asymmetry》2013,24(12):724-728
The stereoselective total synthesis of Ieodomycin A and B, bioactive secondary metabolites from marine sources with potent anti-microbial activity was achieved starting from commercially available geranial. The key steps involved in the synthetic sequence of Ieodomycin A and B are the Sharpless asymmetric epoxidation, the formation of a β-ketoester, and the 1,3-anti reduction. The synthesis of C-3 epimer of Ieodomycin A and B was also accomplished in good yields. 相似文献
62.
We have developed an efficient method to deacetylate the aromatic acetates using NaOAc in excellent yields and demonstrated the application of the procedure in the synthesis of natural products. 相似文献
63.
The synthesis and encapsulation of M+n-octamethylcalix(4)pyridino complexes using acetone and pyridine in H-MCM-41 have been achieved and presented. These hybrid catalysts are characterized by x-ray diffraction, infrared, thermal analysis, Brunauer–Emmett–Teller (BET) surface area, and scanning electron microscopy and tested for catalytic activity. They are active in the liquid-phase oxidation of p-xylene using H2O2 as oxidant and acetic acid as solvent in the temperature range of 30–100 °C. The variation of central transition-metal cation and the heterocyclic ring in the metallomacrocycle influence the catalytic activity. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
64.
A new chemical access has been developed to synthesize biaryls from substituted acetophenones, phenylacetones, dihydrochalcone, and 2-acetylnaphthalene in reasonably good yields at room temperature via a domino reaction sequence of AlCl(3) catalyzed cyclization, dehydration, and then oxidation. 相似文献
65.
We have developed an efficient method to regioselectively deacetylate polyacetoxyacetophenones using BF3·OEt2 in excellent yields and demonstrated the application of the procedure in the synthesis of natural products. 相似文献
66.
Burling S Paine BM Nama D Brown VS Mahon MF Prior TJ Pregosin PS Whittlesey MK Williams JM 《Journal of the American Chemical Society》2007,129(7):1987-1995
A series of ruthenium hydride N-alkyl heterocyclic carbene complexes has been investigated as catalysts for a tandem oxidation/Wittig/reduction reaction to give C-C bonds from alcohols. The C-H-activated carbene complex Ru(IiPr(2)Me(2))'(PPh(3))(2)(CO)H (9) proves to be the most active precursor catalyzing the reaction of PhCH(2)OH and Ph(3)P=CHCN in 3 h at 70 degrees C. These results provide (a) a rare case in which N-alkyl carbenes afford higher catalytic activity than their N-aryl counterparts and (b) a novel example of the importance of NHC C-H activation in a catalytic cycle. 相似文献
67.
Summary Cobalt(II), nickel(II), palladium(II) and platinum(II) complexes witho-(OCD),m-(MCD) andp-chlorophenyldithiocarbamate (PCD) ligands have been synthesised and characterised by chemical analyses, molecular weight determinations, conductance measurements, electronic and i.r. spectral studies. The thermal behaviour of the complexes has been studied by t.g. and d.t.a. techniques in a static air atmosphere and heats of reaction of different decomposition steps have been calculated from the d.t.a. curves. The thermal decomposition products of the complexes were identified by elemental analyses and i.r. spectra. 相似文献
68.
New chemical access has been developed for the synthesis of pyran core embedded derivatives from 1,3-diketones and 1,3-diketoesters, in which the active methylene group of 1,3-diketone or 1,3-diketoester was alkenylated with three equivalents of alkenyl bromides in presence NaH to give bisalkenyl 1,3-diketones or 1,3-diketoesters and the resultant bisalkenyl 1,3-diketones or 1,3-diketoesters were reacted with AlCl3 at room temperature to furnish pyran core embedded derivatives in good to excellent yields. 相似文献
69.
Shyam Sunder Anchuri Sreekanth Thota Raja Narender Bongoni Rajeshwar Yerra Rama Narsimha Reddy Satyavati Dhulipala 《中国化学会会志》2013,60(2):153-159
The present work was aimed that the two Ruthenium compounds namely, [Ru(A)2(B)]Cl2, where A = 1,10‐phenanthroline; B = 2‐NO2‐phenyl thiosemicarbazone (Compound R1)/2‐OH‐phenyl thiosemicarbazone (Compound R2) have been tested for antibacterial activity at the concentrations of 1 mg/mL against various Gram‐Positive organisms (Lactobacillus, Staphylococcus pyrogenes, Bacillus subtilis, Staphylococcus aureus & Bacillus megatarium) and Gram‐Negative organisms (Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Enterobacter aerogenes, Salmonella paratyphi, Klebsiella pneumonia & Proteus mirabilis). The compounds were also tested for antifungal activity against Aspergillus clavatus, Aspergillus niger, Colletotrichum & Penicillium notatum by using agar diffusion assay and antimalarial activity against Plasmodium falciparum (Strain 3D7) using MTT assay. The results concluded that the compound R1 exhibited significant antibacterial activity than R2 against Gram‐Negative bacteria with zones of inhibition ranging from 15‐20 mm. and mild antibacterial activity against Gram‐Positive bacteria in comparison to tetracycline, streptomycin and rifampicin. These complexes were found to have moderate antifungal activity with no activity was however observed against Aspergillus niger. The compound, R1 exhibited antimalarial activity at 10 μg/mL, whereas R2 did not show antimalarial activity upto 50 μg/mL. Sensitivity to the compounds was greatest in the gram‐negative bacteria, followed by the gram‐positive bacteria and fungi. 相似文献
70.
Venkateshwarlu Gurram Dr. Narender Pottabathini Ramesh Garlapati Dr. Avinash B. Chaudhary Dr. Balaram Patro Prof. Mahesh K. Lakshman 《化学:亚洲杂志》2012,7(8):1853-1861
Reaction conditions for the C? C cross‐coupling of O6‐alkyl‐2‐bromo‐ and 2‐chloroinosine derivatives with aryl‐, hetaryl‐, and alkylboronic acids were studied. Optimization experiments with silyl‐protected 2‐bromo‐O6‐methylinosine led to the identification of [PdCl2(dcpf)]/K3PO4 in 1,4‐dioxane as the best conditions for these reactions (dcpf=1,1′‐bis(dicyclohexylphosphino)ferrocene). Attempted O6‐demethylation, as well as the replacement of the C‐6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd‐cleavable groups such that C? C cross‐coupling and O6‐deprotection could be accomplished in a single step. Thus, inosine 2‐chloro‐O6‐allylinosine was chosen as the substrate and, after re‐evaluation of the cross‐coupling conditions with 2‐chloro‐O6‐methylinosine as a model substrate, one‐step C? C cross‐coupling/deprotection reactions were performed with the O6‐allyl analogue. These reactions are the first such examples of a one‐pot procedure for the modification and deprotection of purine nucleosides under C? C cross‐coupling conditions. 相似文献