نتایج جستجو برای: conjugate addition reaction
تعداد نتایج: 1118710 فیلتر نتایج به سال:
[reaction: see text] There have been a number of reports of the kinetic conjugate (1,4) addition of metalated arylacetonitriles to enones. Several proposals have been made to explain this behavior based on nucleophile structure or aggregation state or on the HSAB properties of the reactants. A reexamination of these studies showed that in each case the 1,4 adducts resulted from equilibration of...
Conjugate addition of organocopper reagents to ct,-ethylenic aldehydes is discussed. Use of cz,r3-ethylenic aminals is an— other approach to the same target, namely homologation of R-M to an aldehyde with three more carbon atoms. The c,-ethylenic aldehydes are easily prepared by carbocupration of c,13-acetylenic acetals. A new way to cz,t3-ethylenic ketones, mediated by organo copper reagents i...
The impact of browning intensity on interfacial properties gellan gum-soy protein conjugate obtained through the Maillard reaction
N-heterocyclic moieties are abundant among pharmaceuticals and agrochemicals, but a challenge for metalorganic organocatalytic transformations. We present tripeptides of the type H-Pro-Pro-Xaa as catalysts stereoselective conjugate addition reactions between substituted aldehydes electrophiles. Alkyl substituents at N-terminal proline, reactive site, were crucial high chemo- stereoselectivity. ...
A mechanism is proposed for the formation of cyclic 5,6,7,8,9-pentathiabenzocycloheptene-1,2-diol, 4, from the reaction of o-benzoquinone with reduced elemental sulfur, H2Sx. 1,6-conjugate addition to the quinone is favored over 1,4-conjugate addition. Hydrogen bonding to the quinone oxygen enhances the nucleophilicity of H2Sx by facilitating the removal of the S-H proton. We propose that initi...
ABSTRACT Most of physiological effects of bradykinin is due to its effect on bradykinin B2 receptors. There is no reports of preparation of a photoactivatable analogue of bradykinin reactive with sloubilized bradykinin B2 recpetors. Photoactivatable radioactive ligands are powerful tools in purification of receptors. In this study we report preparation of a photoactivatable iodinatable analo...
Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and acetylenic esters, by NH-acids such as azathioprine, imidazole or theophylline leads to the formation of vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce phosphorus ylides. Silica nanoparticles (silica NPs were prepared by therm...
DNA metabolism is based on formation of different DNA-protein complexes which can adopt various conformations. To characterize functioning of such complexes, one needs a solution-based technique which allows fixing a complex in a certain transient conformation. The crosslinking approach is a popular tool for such studies. However, it is under debate if the protein components retain their natura...
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