نتایج جستجو برای: nucleophilic displacement
تعداد نتایج: 59517 فیلتر نتایج به سال:
A V(III) thiolate complex activated C-Cl bond in dichloromethane via S-based nucleophilic attack. The reaction products, a V(III)-Cl species (major one) and a V(IV) binding to a CH(2) containing ligand (minor one) were obtained. The work demonstrates sulfur donors in the early-transition metal thiolates having strong nucleophilic characteristics.
A nucleophilic catalysis method providing a concise synthesis of di-, tri-, and tetrasubstituted pyrroles is described. This regioselective one-pot method relies on nucleophilic catalysis of the intermolecular addition of oximes to activated alkynes and thermal rearrangement of the in situ generated O-vinyl oximes to form pyrroles that contain a functional group handle at the C3/C4 position.
A new synthetic approach to polyfunctional hexahydropyrrolo[3,4-b]pyrroles was developed based on cyclization of N-arylbromomaleimides with aminocrotonic acid esters. A highly chemo- and stereoselective reaction is a Hantzsch-type domino process, involving the steps of initial nucleophilic C-addition or substitution and subsequent intramolecular nucleophilic addition without recyclyzation of im...
The anionic and the cationic partners of ionic liquids may act cooperatively and independently as nucleophilic and electrophilic catalysts. This ambiphilic propensity was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) to the solvent-free Baylis– Hillman dimerization of cyclohexenone catalysed by ionic ...
The possibility of tunable regioselective activation of a dinitrile towards nucleophilic attack was demonstrated. For that, a sulfo-arylhydrazone unit was introduced into malononitrile and the thus formed intramolecular hydrogen bond systems assisted specific nucleophilic attacks to the cyano moieties leading to a variety of amidines, carboxamides and iminoesters depending on the nucleophiles a...
Dedicated to Professor Heinrich Nöth on the occasion of his 85th birthday The nucleophile-specific parameters N and sN, as defined by the linear free energy relationship log k = sN(N +E) (J. Am. Chem. Soc. 2001, 123, 9500 – 9512), were determined for five imines 1a–e by studying the kinetics of their reactions with benzhydrylium ions in dichloromethane solution at 20 ◦C. These parameters allowe...
Organic phosphonium salts have served as important intermediates in synthetic chemistry. But the use of a substituent on the positive phosphorus as a nucleophile to construct C-C bond remains a significant challenge. Here we report an efficient transition-metal-free protocol for the direct nucleophilic arylation of carbonyls and imines with tetraarylphosphonium salts in the presence of caesium ...
This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita-Baylis-Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates, Michael additions, γ-umpolung additions, an...
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