نتایج جستجو برای: selectivity of products
تعداد نتایج: 21179743 فیلتر نتایج به سال:
A high-speed, highly efficient chemoselective N-acylation by anhydride was achieved in the absence of catalyst for exothermic (DeltaH>0) and endothermic (DeltaH<0) acylation of various amines and anilines with the microreaction system of ambient water (micro-onH2O) and subcritical water (micro-subH2O), where the desired N-acylated products are chemoselectively obtained with high yield(s) and ex...
The palladium-catalyzed decarboxylative allylic alkylation of diastereomeric β-ketoesters derived from 4-tert-butylcyclohexanone is described. These experiments were performed to elucidate our understanding of stereoablative enantioconvergent catalysis. A detailed analysis of the product distribution, including stereochemical outcome of the products, is included. These studies also reveal an in...
The catalytic, asymmetric syntheses of quinine and quinidine were achieved in 16 steps. The recently developed salen(Al)-catalyzed enantioselective Michael addition of methyl cyanoacetate served to set the crucial C4 stereocenter in 92% ee, and a late-stage asymmetric dihydroxylation was used to differentiate the common intermediate and access the two desired diastereomeric products with high s...
A continuous protocol for the two-carbon homologation of esters to α,β-unsaturated esters is described. This multireactor homologation telescopes an ester reduction, phosphonate deprotonation, and Horner-Wadsworth-Emmons olefination, thus converting a three-operation procedure into a single, uninterrupted system that eliminates the need for isolation or purification of the aldehyde intermediate...
A novel and efficient synthesis of 2-bromo(chloro)-3-selenyl(sulfenyl)indoles through tandem reactions of 2-(gem-dibromo(chloro)vinyl)-N-methylsulfonylanilines with diselenides and disulfides in the presence of t-BuOLi and I(2) (10 mol%) in DMSO was developed. The reactions generated the desired products in good yields with high regio-selectivity under transition-metal-free conditions in one-pot.
The first Ni-promoted prototype reaction based on the tandem C-H activation of heteroarenes with alkene isomerization is demonstrated, leading to the branched hydroheteroarylation products. Simultaneously, the reaction selectivity can be chemically switched to linear adducts through Ni-Al tandem catalysis.
A structurally simple, highly reactive chlorinating reagent, N-chloro-N-fluorobenzenesulfonylamine (CFBSA), was conveniently prepared from inexpensive Chloramine B in high yield. A wide range of substrates were chlorinated with it to obtain products in good to high yields and appropriate selectivity.
abstract sensitive and precise voltammetric methods for the determination of trace amounts of furaldehydes, mainly as furfural (f) and 5-hydroxymethyl-2-furaldehyde (hmf), in waste waters and other matrices is described. determination of total furaldehyde at < ?g g-1 levels in alkaline buffered aqueous media was individually investigated. by the use of ordinary swv and adsorptive square wave ...
Electrolytes have a profound impact on the chemical environment of electrocatalysis, influencing reaction rate and selectivity products. In article 2300628, Xinxin Lu, Wenguang Tu, Yong Zhou, Zhigang Zou summarize recent progress in understanding effects various electrolyte ionic species diverse electrocatalytic reactions.
Direct conversion of CH4 and CO2 to liquid fuels chemicals under mild conditions is appealing for biogas utilization but challenging due the inert nature both gases. Herein, we report a promising plasma process catalyst-free single-step into higher value oxygenates (i.e., methanol, acetic acid, ethanol, acetone) at ambient pressure room temperature using water-cooled dielectric barrier discharg...
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