نتایج جستجو برای: electrophilic coupling agent
تعداد نتایج: 405108 فیلتر نتایج به سال:
A practical and highly stereoselective approach to access 2,6-disubstituted piperidines using an amidine auxiliary is reported. Following the diastereoselective addition of Grignard reagents at the 2-position of an activated pyridinium salt, the amidine group directs a regioselective metalation at the 6-position, enabling further functionalization. A subsequent electrophilic quench or a Negishi...
Based on a preactivation protocol with (p-Tol)2SO/Tf2O, a practical, straightforward, and high-yielding synthesis of α-sialyl C-glycosides was accomplished by coupling N-acetyl-5-N,4-O-oxazolidione protected thiosialoside with various trimethylsilyl enol ethers and allyltrimethylsilanes. High yields and excellent α-selectivities were obtained for the strong π-nucleophiles with large nucleophili...
A one pot green three‐component coupling reaction of aldehyde, phenylacetylene, and amine derivatives in the presence of copper (II)–thioamide combination as a novel and efficient heterogeneous catalyst under solvent–free conditions is reported. The catalyst displayed high activity and afforded the corresponding propargylamines in good to high yields. The key to this procedure was the generatio...
The electrophilic eicosanoids prostaglandins A(1) or A(2) impaired p53-dependent transcription of endogenous genes and exogenous p53-luciferase reporter plasmids in RKO and HCT 116 colon cancer cells. Cellular accumulation of genetically wild-type, but transcriptionally silent p53 varied as a function of exposure time and concentration of prostaglandins A(1) and A(2). Prostaglandins A(1) and A(...
A wide array of cross-coupling methods for the formation of C-C bonds from unactivated alkyl electrophiles have been described in recent years. In contrast, progress in the development of methods for the construction of C-heteroatom bonds has lagged; for example, there have been no reports of metal-catalyzed cross-couplings of unactivated secondary or tertiary alkyl halides with silicon nucleop...
Atropo-enantioselective biaryl coupling through C−H bond functionalization is an emerging technology allowing direct construction of axially chiral molecules. This approach largely limited to electrophilic partners. We report a highly atropo-enantioselective arylation tetralone derivatives paired with aryl boronic esters as nucleophilic components. The transformation catalyzed by cyclopentadien...
The enantiospecific conversion of chiral secondary boronic esters into alkylfluorides is reported. Boronate complexes derived from boronic esters and PhLi were used as nucleophiles, with Selectfluor II as the electrophilic fluorinating agent, to afford alkylfluorides in short reaction times. The addition of styrene as a radical trap was found to enhance enantiospecificity. A broad range of alky...
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