نتایج جستجو برای: carbene reaction
تعداد نتایج: 419291 فیلتر نتایج به سال:
A new method for the direct synthesis of imines from alcohols and amines is described where hydrogen gas is liberated. The reaction is catalyzed by the ruthenium N-heterocyclic carbene complex [RuCl2(IiPr)(p-cymene)] in the presence of the ligand DABCO and molecular sieves. The imination can be applied to a variety of primary alcohols and amines and can be combined with a subsequent addition re...
This article proposes to bridge two fields, namely organometallics and quantum chemical topology. To do so, Palladium-catalyzed reductive elimination is studied. Such reaction is a classical elementary step in organometallic chemistry, where the directionality of electrons delocalization is not well understood. New computational evidences highlighting the accepted mechanism are proposed followi...
α-Imino gold carbenoid species have been recognized as key intermediates in a plethora of processes involving gold-activated alkynes. Here, we explored the pathways Au(I)-catalyzed [3 + 2] reaction between mild nucleophiles: anthranil, 1,2,4-oxadiazole, or 4,5-dihydro-1,2,4-oxadiazole, and an ynamide, PhC≡C-N(Ts)Me, proceeding via formation aforementioned α-imino carbene intermediate which, aft...
Rh(CO)2Cl(NHC) complexes of dipyrido-annelated N-heterocyclic carbenes were prepared. From the C-H coupling constant of the respective imidazolium salts and the N-C-N angle of the N-heterocyclic carbene (NHC), a weaker σ-donor character than that of typical unsaturated NHCs is expected. However, the IR stretching frequencies of their Rh(CO)2Cl complexes suggest an electron-donor character even ...
An (amino)(phosphino) carbene can be transformed into (amino)(phosphonio) carbenes, which undergo nucleophilic intermolecular as well as intramolecular substitution reactions at the carbene center. A variety of carbenes can be synthesized starting from a single carbene precursor. The resulting gamut of electronic and steric effects possible should open the way not only to a detailed study of th...
Exciting new variations in Fischer-type carbene complex composition and reactivity have been realised by following or modifying well-established synthetic approaches such as metal carbonyl functionalization and modification of existing carbene ligands. The formation of targeted complexes for organic synthesis, carbene-containing chelates, and polynuclear carbene complexes, by employing 'click c...
The cationic [NiCp(Mes-NHC-CH2py]Br complex 2 a was prepared directly by the reaction of nickelocene with 1-(2-picolyl)-3-mesityl-imidazolium bromide (1), and its PF6? derivative b, subsequent salt metathesis. X-ray diffraction studies Variable Temperature 1H NMR experiments run b strongly suggest bidentate coordination picolyl-functionalized carbene to nickel both in solid state solution cases...
By reviewing the recent progress on the elucidation of the structure of gold carbenes and the definitions of metal carbenes and carbenoids, we recommend to use the term gold carbene to describe gold carbene-like intermediates, regardless of whether the carbene or carbocation extreme resonance dominates. Gold carbenes, because of the weak metal-to-carbene π-back-donation and their strongly elect...
The reaction of MesP=CPh2 with the least sterically demanding N-heterocyclic carbene (NHC = IMe) results in formation of the 'abnormal' (C(4)-substituted) 4-phosphino-NHC (1). In contrast, reaction with Me2IMe gives the unprecedented 'normal' C(2) adduct, Me2IMe → P(Mes)=CPh2 (2). Particularly striking is the asymmetric and weak bonding of the NHC to the P=C moiety in 2. DFT calculations indica...
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