Cat’s claw oxindole alkaloids are prone to isomerization in aqueous solution. However, studies on their behavior in extraction processes are scarce. This paper addressed the issue by considering five commonly used extraction processes. Unlike dynamic maceration (DM) and ultrasound-assisted extraction, substantial isomerization was induced by static maceration, turbo-extraction and reflux extrac...

Mixed crystals of 1-(4-chlorophenylsulfonyl)-2,5-dimethyl-1 H -benzimidazole and 1-(4-chlorophenylsulfonyl)-2,6-dimethyl-1 (ratio 0.707:0.293; two molecules in the asymmetric unit), 0.707C 15 13 ClN 2 O S·0.293C S, ( I ), 2- n -butyl-1-(4- tert -butylphenylsulfonyl)-5-chloro-1 -butylphenylsulfonyl)-6-chloro-1 [ratio 0.731 (2):0.269 (2); one molecule unit], 0.731C 21 25 S·0.269C II were obtained...

The enantioselective α-vinylation of aldehydes using vinyl iodonium triflate salts has been accomplished via the synergistic combination of copper and chiral amine catalysis. These mild catalytic conditions provide a direct route for the enantioselective construction of enolizable α-formyl vinylic stereocenters without racemization or olefin transposition. These high-value coupling adducts are ...

We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stere...

An efficient rhodium/olefin-sulfoxide catalyzed asymmetric conjugate addition of organoboronic acids to a variety of nitroalkenes has been developed, where 2-methoxy-1-naphthyl sulfinyl functionalized olefin ligands have shown to be highly effective and are applicable to a broad scope of aryl, alkyl, and heteroaryl nitroalkenes.

An iron-catalyzed enantioselective and diastereoselective intramolecular olefin aminochlorination reaction is reported (ee up to 92%, dr up to 15 : 1). In this reaction, a functionalized hydroxylamine and chloride ion are utilized as nitrogen and chlorine sources, respectively. This new method tolerates a range of synthetically valuable internal olefins that are all incompatible with existing a...

the present work is focused on the degradation of 4-chloro-2-nitrophenol in aqueous solution containing nano titanium dioxide, hydrogen peroxide and the combination of nano-tio2/h2o2. the effect of experimental parameters, such as the amount of nano- tio2 concentration of h2o2, initial concentration of 4-chloro-2-nitrophenol and ph on the reaction was investigated. experimental data obtained un...

Spectral and kinetic behavior of thermal cis-to-trans isomerization of 4-aminoazobenzene (AAB) is examined in various solvents of different polarities. In contrast to azobenzene (AB), it is found the rate of thermal isomerization of AAB is highly dependent on solvent polarity. Accelerated rates are observed in polar solvents as compared to nonpolar solvents. Moreover, a decrease in the barrier ...