We report in this paper a facile approach for the formation and electrochemical characterization of silver-silver oxide core-shell nanoparticles (NPs). Thus, thermal treatment at temperatures between 200 and 360 degrees C of Ag NP, in the gas phase or in an organic solvent, has been used to achieve the formation Ag@Ag2O NP. The evidence of formation of such a core-shell structure was obtained by cyclic voltammetry using a Nafion modified electrode (where Nafion containing carbon particles is used as the matrix to encapsulate the core-shell NP). Initial positive scans measure free Ag. Initial negative scans measure Ag2O, with the following positive scan, compared to the initial one, providing a measure of "trapped" or core Ag. The results presented demonstrate the utility of this approach in characterizing core-shell structures, like Ag@Ag2O, which could be extended to other core-shell forms, such as bimetallic core-shell NP.
Process
research and development of the first fully synthetic broad
spectrum 7-fluorotetracycline in clinical development is described.
The process utilizes two key intermediates in a convergent approach.
The key transformation is a Michael–Dieckmann reaction between
a suitable substituted aromatic moiety and a key cyclohexenone derivative.
Subsequent deprotection and acylation provide the desired active pharmaceutical
ingredient in good overall yield.
A robust, cost effective and high yielding manufacturing process for enantiomerically enriched (S)-allylic amine 3, a key intermediate for fully synthetic tetracyclines have been developed.Two novel and scalable asymmetric vinylations resulting in high to excellent stereoselectivity have been developed for the key step. The final product is purified by an efficient crystallization of a L-tartaric salt. The process described has been used to manufacture ~350 kg of the tartaric salt of 3 with 99.0% ee in 8 steps (35% overall yield) from cheap and readily available dimethyl maleate.
A convergent route to eravacycline (1) has been developed by employing Michael-Dieckmann cyclization between enone 3 and a fully built and protected left-hand piece (LHP, 2). After construction of the core eravacycline structure, a deprotection reaction was developed, allowing for the isoxazole ring opening and global deprotection to be achieved in one pot. The LHP is synthesized from readily available 4-fluoro-3-methylphenol in six steps featuring a palladium-catalyzed phenyl carboxylation in the last step.
Process
research and development of the fully synthetic broad spectrum
tetracycline TP-2758, with a chiral pyrrolidine side chain at the
C-8 position, is described. The process utilizes two key intermediates, 7 and 10, in a convergent approach that allows
for manufacturing of sufficient quantities of API to supply preclinical
and early clinical development. The pyrrolidine moiety was introduced
into the left-hand piece (LHP) 10 with high enantioselectivity
using Ellman’s sulfinamide chemistry, and the absolute configuration
was confirmed by X-ray crystal structure analysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.