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1.
Nsevolo Samba Radhia Aitfella-Lahlou Mpazu Nelo Lucia Silva Rui Coca. Pedro Rocha Jesus Miguel Lpez Rodilla 《Molecules (Basel, Switzerland)》2021,26(1)
The purpose of the study was to determine the chemical composition and antibacterial activity of Lippia multiflora Moldenke essential oils (EOs) collected in different regions of Angola. Antibacterial activity was evaluated using the agar wells technique and vapour phase test. Analysis of the oils by GC/MS identified thirty-five components representing 67.5 to 100% of the total oils. Monoterpene hydrocarbons were the most prevalent compounds, followed by oxygenated monoterpenes. The content of the compounds varied according to the samples. The main components were Limonene, Piperitenone, Neral, Citral, Elemol, p-cymene, Transtagetone, and Artemisia ketone. Only one of the eleven samples contained Verbenone as the majority compound. In the vapour phase test, a single oil was the most effective against all the pathogens studied. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) of components of the selected EOs and inhibition zone diameter values of agar wells technique allowed us to identify a variability between the plants from the two provinces, but also intraspecific variability between sub-groups within a population. Each group of essential oils constituted a chemotype responsible for their bacterial inhibition capacity. The results presented here suggest that Angolan Lippia multiflora Moldenke has antibacterial properties and could be a potential source of antimicrobial agents for the pharmaceutical and food industry. 相似文献
2.
A scalable synthesis of 5-substituted-2-amino-1,3,4-oxadiazoles via oxidation of a thiosemicarbazide precursor is described. The thiosemicarbazide intermediates are easily accessed from the corresponding acid chlorides. Oxidative cyclization using 1,3-dibromo-5,5-dimethylhydantoin as the primary oxidant, in the presence of potassium iodide, gives a variety of oxadiazoles in good yields. This methodology utilizes a commercially inexpensive and easily handled oxidant. 相似文献
3.
Dr. Haifeng Yang Dr. Peter G. Dormer Nelo R. Rivera Dr. Andrew J. Hoover 《Angewandte Chemie (International ed. in English)》2018,57(7):1883-1887
Tritium‐labeled molecules are critical tools for elucidating the binding and metabolic properties of bioactive compounds, particularly during pharmaceutical discovery. Direct tritiation of inert C?H bonds with T2 gas is an ideal approach for tritium labeling, but significant gaps remain for direct tritiation of structurally complex molecules with diverse functional groups. Here we report the first application of palladium(II) C?H activation chemistry for tritiation with T2 gas. This practical transformation exhibits novel substrate scope and greater functional group tolerance compared to previous state of the art tritiation methods, and has been applied to directly tritiate 9 complex pharmaceuticals and an unprotected dipeptide. The isolated tritium‐labeled products exhibit >15 Ci mmol?1 specific activity, exceeding the typical requirements for application in studies of molecular interaction and metabolism. 相似文献
4.
Cai C Rivera NR Balsells J Sidler RR McWilliams JC Shultz CS Sun Y 《Organic letters》2006,8(22):5161-5164
Aryl carboxylic esters were synthesized by Pd-catalyzed carbonylation of aryl p-fluorobenzenesulfonates or -tosylates. A unique Josiphos ligand was discovered through high-throughput catalyst screening, which was the key for the successful carbonylation of various substrates. This catalyst is effective and works well for both electron-rich and electron-poor aryl arenesulfonates. Isolated yields of up to 90% were obtained for aryl p-fluorobenzenesulfonates and -tosylates. [reaction: see text] 相似文献
5.
MK-7655 (1) is a β-lactamase inhibitor in clinical trials as a combination therapy for the treatment of bacterial infection resistant to β-lactam antibiotics. Its unusual structural challenges have inspired a rapid synthesis featuring an iridium-catalyzed N-H insertion and a series of late stage transformations designed around the reactivity of the labile bicyclo[3.2.1]urea at the core of the target. 相似文献
6.
Ikemoto N Tellers DM Dreher SD Liu J Huang A Rivera NR Njolito E Hsiao Y McWilliams JC Williams JM Armstrong JD Sun Y Mathre DJ Grabowski EJ Tillyer RD 《Journal of the American Chemical Society》2004,126(10):3048-3049
Pure (Z)-enamines readily prepared from beta-ketoesters and amides using (S)-phenylglycine amide were hydrogenated with very high diastereoselectivities (up to 200:1) using heterogeneous catalysis. Hydrogenolytic cleavage of the (S)-phenylglycine amide afforded the corresponding chiral beta-aminoesters and amides. The high geometrical purity of the (Z)-enamine and a simple activation procedure for the PtO2 catalyst are essential in achieving high selectivity. 相似文献
7.
Zheng Tan Yong Liu Roy Helmy Nelo R. Rivera David Hesk Sriram Tyagarajan Lu Yang Jing Su 《Tetrahedron letters》2017,58(31):3014-3018
Aromatic CH bromination is one of the applications of late stage functionalization that provides precursors for generation of radio-labelled compounds to support drug metabolism and pharmacokinetic (DMPK) studies or provide a “handle” for further functionalization to expand SAR studies without having to resort to de novo synthesis. Electrochemical aromatic bromination was attempted on late stage intermediates and drug molecules such as cytidine, uridine, Tenofovir, MK-4618, Sch48973 and MK-8457. The reactions were conducted under mild galvanostatic electrolysis condition in aqueous NaBr solution. The brominated products were obtained and converted to the corresponding tritium labelled products. Electrochemical methodology provides an alternative way to quickly generate aryl bromides of late stage intermediates or drug molecules that are very useful in drug discovery. 相似文献
8.
Hartner FW Hsiao Y Eng KK Rivera NR Palucki M Tan L Yasuda N Hughes DL Weissman S Zewge D King T Tschaen D Volante RP 《The Journal of organic chemistry》2004,69(25):8723-8730
The preparation of 3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propan-1-amine 2a and 3-[(7R)-7-methyl-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl]propan-1-amine 2b, key intermediates in the synthesis of alpha(V)beta(3) antagonists, is described. The syntheses rely on the efficient double Sonogashira reactions of 2,5-dibromopyridine 3 with acetylenic alcohols 4a/4b and protected propargylamines 10a-e followed by Chichibabin cyclizations of 3,3'-pyridine-2,5-diyldipropan-1-amines 9a/9b. 相似文献
9.
Yasuda N Hsiao Y Jensen MS Rivera NR Yang C Wells KM Yau J Palucki M Tan L Dormer PG Volante RP Hughes DL Reider PJ 《The Journal of organic chemistry》2004,69(6):1959-1966
A practical preparation of an alpha(v)beta(3) antagonist is reported. The antagonist consists of three key components, a tetrahydronaphthyridine moiety, a beta-alanine moiety, and a central imidazolidone moiety. The tetrahydronaphthyridine component was prepared using two different methods, both of which relied on variations of the Friedl?nder reaction to establish the desired regiochemistry. The beta-alanine component was prepared using Davies' asymmetric 1,4-addition methodology as the key stereo-defining step. The central imidazolidone portion was created from these two components using an effective three-step cyclization protocol. Thus, a highly convergent process for the drug candidate was defined. 相似文献
10.
Hsiao Y Rivera NR Rosner T Krska SW Njolito E Wang F Sun Y Armstrong JD Grabowski EJ Tillyer RD Spindler F Malan C 《Journal of the American Chemical Society》2004,126(32):9918-9919
A direct asymmetric hydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives beta-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required. 相似文献