排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
The presence of aryl sulfides in biologically active compounds has resulted in the development of new methods to form carbon-sulfur bonds. The synthesis of aryl sulfides via metal catalysis has significantly increased in recent years. Historically, thiolates and sulfides have been thought to plague catalyst activity in the presence of transition metals. Indeed, strong coordination of thiolates and thioethers to transition metals can often hinder catalytic activity; however, various catalysts are able to withstand catalyst deactivation and form aryl carbon-sulfur bonds in high-yielding transformations. This review discusses the metal-catalyzed arylation of thiols and the use of disulfides as metal-thiolate precursors for the formation of C-S bonds. 相似文献
2.
The synthesis of 1H-indazoles is achieved from o-aminobenzoximes by the selective activation of the oxime in the presence of the amino group. The reaction occurs with a variety of substituted o-aminobenzoximes using a slight excess of methanesulfonyl chloride and triethylamine at 0-23 degrees C and is amenable to scale-up. The synthesis of 1H-indazoles under these conditions is extremely mild compared with previous synthetic approaches and affords the desired compounds in good to excellent yields. 相似文献
3.
Stability of florfenicol in drinking water 总被引:1,自引:0,他引:1
Florfenicol, a broad-spectrum antibiotic, is being developed for veterinary application as an oral concentrate intended for dilution with drinking water. When a drug product is dosed via drinking water in a farm setting, a number of variables, including pH, chlorine content, hardness of the water used for dilution, and container material, may affect its stability, leading to a decrease in drug potency. The stability of florfenicol after dilution of Florfenicol Drinking Water Concentrate Oral Solution, 23 mg/mL, with drinking water was studied. A stability-indicating, validated liquid chromatographic method was used to evaluate florfenicol stability at 25 degrees C at 5, 10, and 24 h after dilution. The results indicate that florfenicol is stable under a range of simulated field conditions, including various pipe materials and conditions of hard or soft and chlorinated or nonchlorinated water at low or high pH. Significant degradation (> 10%) was observed only for isolated combinations in galvanized pipes. Analysis indicated that the florfenicol concentration in 8 of the 12 water samples stored in galvanized pipes remained above 90% of the initial concentration (100 mg/L) for 24 h after dilution. 相似文献
4.
A comparison of electrospray ionization,atmospheric pressure chemical ionization,and atmospheric pressure photoionization for the liquid chromatography/tandem mass spectrometric analysis of bisphenols. Application to bisphenols in thermal paper receipts and U.S. currency notes 下载免费PDF全文
5.
Pd‐Catalyzed Carboamination of Alkylidenecyclopropanes: Synthesis of Congested Pyrrolidines and Piperidines 下载免费PDF全文
Phillip R. Lazzara Keegan P. Fitzpatrick Dr. Chad C. Eichman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16779-16782
The synthesis of densely functionalized N‐heterocycles is an ongoing challenge in chemical synthesis. Herein, we report an efficient method for the construction of pyrrolidine and piperidine scaffolds using a palladium‐catalyzed carboamination of alkylidenecyclopropanes. 相似文献
6.
7.
8.
Cohen DT Eichman CC Phillips EM Zarefsky ER Scheidt KA 《Angewandte Chemie (International ed. in English)》2012,51(29):7309-7313
New DKR type: An N-heterocyclic carbene (NHC)-catalyzed dynamic kinetic resolution of racemic α-substituted β-keto esters has been developed. This method relies on the epimerization of an NHC-enol intermediate before subsequent aldol/acylation events. Highly substituted β-lactones are produced in good yield with good to excellent selectivities (see scheme). 相似文献
9.
Bielinska Anna Eichman Jonathan D. Lee Inhan Baker James R. Balogh Lajos 《Journal of nanoparticle research》2002,4(5):395-403
Dendrimer nanocomposites (DNC) are hybrid nanoparticles formed by the dispersion and immobilization of guest atoms or small clusters in dendritic polymer matrices. They have a great potential in biomedical applications due to their controlled composition, predetermined size, shape and variable surface functionalities. In this work, d=5–25nm spherical nanoparticles composed of gold and poly(amidoamine) (PAMAM) dendrimers have been selected to demonstrate this nanoparticle based concept. {Au(0)n-PAMAM} gold dendrimer nanocomposites with a well-defined size were synthesized and imaged by transmission electron microscopy both in vitro and in vivo. DNC have also the potential to be used for imaging and drug delivery vehicles either by utilizing bioactive guests or through the incorporation of radioactive isotopes, such as Au-198. 相似文献