نتایج جستجو برای: phase transfer catalysis
تعداد نتایج: 893887 فیلتر نتایج به سال:
Owing to the significant biological activities, quinazoline derivatives have drawn more and more attention in the synthesis and bioactivities research. This review summarizes the recent advances in the synthesis and biological activities investigations of quinazoline derivatives. According to the main method the authors adopted in their research design, those synthetic methods were divided into...
Disclosed herein is a stereoselective method for the synthesis of 2,3-furan fused carbocycles bearing adjacent quaternary and tertiary carbon stereocenters. The chemistry is based on an asymmetric addition of β-ketoesters to 2-(1-alkynyl)-2-alkene-1-ones catalysed by natural cinchona alkaloids followed by a silver-catalysed intramolecular cycloisomerisation. By exploiting the distinct catalysis...
The synthesis, complexation properties and catalytic activities under phase-transfer (PT) conditions of differently substituted cyclohexapeptoids are reported. Association constants, for small cationic alkali, and catalytic performances, in a model nucleophilic substitution, are comparable to those of representative crown ethers. Noteworthy, the N-[2-(2-methoxyethoxy)ethyl] side chain derivativ...
in this research mass transfer coefficient under jetting regime in different directions (from dispersed to continuous and continuous to dispersed phase) has been studied using an experimental setup. n-butanol-succinic acid-water with low interfacial tension has been selected as experimental chemical system. the effects of various parameters such as jet velocity, nozzle diameter and the height o...
Experimental evidence is provided for p-methylbenzyl-D-galactonoamidine to function as a true transition state analog for the enzymatic hydrolysis of aryl-β-D-galactopyranosides by β-galactosidase (A. oryzae). The compound exhibits inhibition constants in the low nanomolar concentration range (12-56 nM) for a selection of substrates. Along these lines, a streamlined synthetic method based on ph...
4-Phenyl-1H-1,5-benzodiazepin-2(3H)-one reacts in the pres-ence of a concentrated aqueous solution of sodium hydroxide and a quaternary ammonium salt (as catalyst) in benzene (phase transfer catalysis) with propargyl bromide, affording the title benzodiazepine derivative, C(18)H(14)N(2)O. In the mol-ecule, the mean plane of the propargyl substituent is almost perpendicular with that of the amid...
Cumulative pregnancy rate has been significantly increased since frozen-thawed embryo transfer was applied in ART cycles. This method has become an essential part of IVF/ICSI treatment. Luteal phase support has been proven to be associated with higher rate of live birth rate. Human chorionic gonadotropin (HCG), and progestrone have been successfully used for luteal phase support in ovarian stim...
Disclosed herein is a stereoselective method for the synthesis of 2,3-furan fused carbocycles bearing adjacent quaternary and tertiary carbon stereocenters. The chemistry is based on an asymmetric addition of b-ketoesters to 2-(1-alkynyl)-2-alkene-1-ones catalysed by natural cinchona alkaloids followed by a silver-catalysed intramolecular cycloisomerisation. By exploiting the distinct catalysis...
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