نتایج جستجو برای: nucleophile
تعداد نتایج: 1574 فیلتر نتایج به سال:
The Au(I)-catalysed rearrangement of propargylic esters formed from an ynamide has been studied. The reaction is facile, and when conducted in the presence of a reactive indole nucleophile, leads to a cascade process whereby γ-indolyl α-acyloxyenamides are formed in good yield and excellent E-stereoselectivity.
A tandem NHC-catalyzed aza-benzoin/Michael reaction has been developed as a method to efficiently produce dihydroindenones and pyrrolidinone-containing tricycles. The novel reaction pattern involves tert-butyl aryl(tosyl)methylcarbamates reacting as both electrophile and nucleophile on the same carbon.
2-Phenallyl was found to be a versatile protecting group of primary amines for the asymmetric one-pot three-component synthesis of propargylamines which leads to enantiomeric excess of up to 96%; it can be easily removed with a palladium(0)-catalyzed allylic substitution using 1,3-dimethylbarbituric acid as a nucleophile.
Chiral CuF-catalyzed asymmetric allylation of ketones and ketimines is described. Nucleophile activation via transmetallation (allylboronate to allylcopper), which is facilitated by a cocatalyst [La(OPr)3 or LiO iPr], is key for these reactions. A CuOTf–3KOtBu–DUPHOS complex is a comparably effective catalyst that reduces the required amount of chiral phosphines.
Enantioselective N-heterocyclic carbene-catalyzed nucleophilic dearomatization of alkyl pyridiniums.
NHC-catalyzed nucleophilic dearomatization of alkyl pyridiniums has been achieved to generate 1,4-dihydropyridines with high enantioselectivity. This is a rare example of catalytic, asymmetric addition of a nucleophile to the activated pyridinium that prefers C-4 functionalization leading to the 1,4-dihydropyridine with high selectivity.
Fluorescence-quenched nucleic acid probes with reactive moieties at both the 5' and 3' ends are synthesized and tested for reaction with two adjacent nucleophile-containing DNAs. These probes improve signal to background over singly reactive probes and can discriminate single nucleotide polymorphisms in the target DNA or RNA.
A useful Michael addition reaction using nitroalkanes as the nucleophile and 4-oxo-enoates as the Michael acceptor has been disclosed, and the reaction allows expedient access to functionalized chiral gamma-keto esters in high yields and excellent enantioselectivities (up to 98% ee), with a low catalyst loading.
A series of hydroxybenzoic acid derivatives have shown inhibitory activity against carbonic anhydrase (CA). X-ray crystallography shows that these molecules inhibit not by binding the active site metal ion but by strong hydrogen bonding to the metal-bound water nucleophile. The binding mode observed for these molecules is distinct when compared to other non-metal-binding CA inhibitors.
The bifunctional frustrated BH(-)/B hydridoborate nucleophile/borane Lewis acid pair 6 is prepared starting from the borata-diene 3 by a sequence of sequential protonation/hydride attachment, followed by hydroboration with Piers' borane [HB(C6F5)2]. The trans-1,2-bifunctional system 6 reduced carbon monoxide eventually to the aldehyde product 10.
This paper describes step-economic iodine-mediated construction of functionalized arylazopyrazoles in the presence of catalytic AgNO3 starting from simple β-ketoesters and two equivalents of arylhydrazines. This cascade reaction includes in situα-iodination of β-ketoesters, pyrazol-3-one formation, substitution with a nitrogen nucleophile, and oxidation/aromatization.
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