نتایج جستجو برای: regio and chemoselective
تعداد نتایج: 16827812 فیلتر نتایج به سال:
Speciation of complex mixtures of trace explosives presents a formidable challenge for sensors that rely on chemoselective interfaces due to the unspecific nature of weak intermolecular interactions. Nanomechanical infrared (IR) spectroscopy provides higher selectivity in molecular detection without using chemoselective interfaces by measuring the photothermal effect of adsorbed molecules on a ...
It has been shown for the first time that relatively electron deficient triazolium pre-catalysts promote (at low loadings in the presence of base) highly chemoselective crossed acyloin condensation reactions between aldehydes and a-ketoesters to afford densely functionalized products incorporating a quaternary stereocentre of considerable synthetic potential. Hydroacylation pathways which have ...
At the time when the highly efficient [(18)F]FDG synthesis was discovered by the use of the effective precursor 1,3,4,6-tetra-O-acetyl-2-O-trifluoromethanesulfonyl- β -D-mannopyranose (mannose triflate) for nucleophilic (18)F-substitution, the field of PET in nuclear medicine experienced a long-term boom. Thirty years later, various strategies for chemoselective (18)F-labeling of biomolecules h...
A polymer-assisted solution-phase (PASP) synthesis of lead structure analogues ready for biological testing without the demand for chromatographic purification is described. Carboxylic acids are coupled to the Kenner or Ellman safety catch linker, respectively, activated by methylation or cyanomethylation and subsequently transferred to the 2'-amino group of the 2'-amino-2'-deoxyadenosine scaff...
In situ hydrolyzed acetals were coupled with in situ generated allyl boronates in a one-pot procedure, affording regio- and stereodefined homoallyl alcohols, epoxides and amino alcohols.
Chemoselective hydrogenation of unsaturated aldehyde to alcohol has attracted growing interests in recent years due its widespread applications fine chemicals. However, the C=O bond was thermodynamically and kinetically unfavorable over C=C bond. Thus, obtain from is very difficult most catalytic systems. In this work, ZnAl-hydrotalcite-supported cysteine-capped Au25 nanoclusters were used as p...
The synthesis of capsanthin 1 was accomplished via the C15-cyclopentyl ketone 13 prepared by Lewis acid-promoted regio- and stereoselective rearrangement of the epoxide 12.
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