1,721,057 research outputs found
Reactivity of cyanogen with monocarbonylnickel(0) complexes. Examples of combined oxidative substitution and internal ligand substitution
No full textThe complex [Ni(CO)(dppb)2] (dppb = Ph2P[CH2]4PPh2) undergoes a two-stage reaction with C2N2 in CH2Cl2, at room temperature. The first stage gives almost equivalent quantities of [{Ni(CN)2(dppb)}2] and [Ni(CO)2(dppb)], whereas quantitative conversion of [Ni(CO)2(dppb)] into [{Ni(CN)2(dppb)}2] and CO is obtained in the second stage. The complexes [Ni(CO)(dppb){P(OR)3}](R = Et or Ph) react in a similar way under particular conditions. A kinetic investigation has been carried out on the first system and a reaction mechanism is proposed for its first stage
Simple metal-catalyzed synthesis of functionalized pyrimidines from dicyanogen and 1,3-dicarbonyl compounds
No full text
Synthesis of pyrimidines from β-dicarbonyl compounds and cyanogen: A metal-catalysed one-pot process
No full textHighly functionalized pyrimidines can be prepared in good yields, by a one-pot procedure, from cyanogen and β-dicarbonyl compounds at ambient conditions in dichloroethane in the presence of catalytic amounts of Ni(acac)2 or Cu(acac)2. The pyrimidines obtained were fully characterized by a variety of physicochemical methods. The presence of at least one keto group in the substrate appears to be a necessary condition for the success of the synthesis, which fails, for instance, for dimethyl malonate. A kinetic study on the synthesis of 2-(1-amino-2-acetylbut-1-enonyl)-4- carboxamido-5-acetyl-6-methyl-1,3-diazine has been carried out by employing Cu(acac)2 as catalyst. A crucial step in the catalytic process is an insertion reaction of C2N2 into the C-H methine bond of a metal-co-ordinated 3-cyanoiminomethylpentane-2,4-dionato ligand, which leads to the formation of a carbon-carbon bond. This process characterizes this new pyrimidine synthesis, in that, as a rule, previously known ring-closure reactions implied only carbon-nitrogen bond formation. The simple addition product of C2N2 to acetyl-acetone, 3- cyanoiminomethylpentane-2,4-dione, is found to play an important kinetic role and its reaction with the organometallic ring mentioned above is a second critical process for the success of the ring closure
Kinetics and mechanism of the oxidative addition of cyanogen to [Ni(CO)2(PPh3)2]
No full textThe complex [Ni(CO)2(PPh3)2], (1), reacts with C2N2 in toluene, at 30.0-44.5 °C, to give trans-[Ni(CN)2(PPh3)2], (2), which crystallizes as a clathrate containing 1 mol of C2N2. The reaction mechanism postulated involves preliminary carbon monoxide dissociation from complex (1), followed by competitive cyanogen attack on the three-co-ordinate [Ni(CO)(PPh3)2] intermediate and subsequent oxidative addition
Metal-catalyzed Addition of Fluorinated Beta-oxoamides To Cyanogen - Synthesis and Characterization of the Products and of Related Catalytic Copper(ii) Intermediates
No full textSynthesis and homopolymerization of {bis(2-(acetoacetoxy)ethyl-methacrylate) copper (II)
No full textTin(iv) Chloride-promoted Vs Metal Beta-carbonyl-enolate-catalyzed Reactions of Beta-dicarbonyls With Nitriles
No full text
Reactivity of cyanogen towards compounds containing active hydrogens at carbon. 6. Addition to β-dicarbonylenolato complexes of nickel(II) and ligand ability of bis[1-cyano-2-(1-iminoethyl)butane-1,3-dionate]nickel(II) towards PdCl 2
No full textThe bis-[β-carbonylenolato)nickel(II) complexes [Ni(eaa) 2] (eaa = ethylacetoacetato), [Ni(ba) 2] (ba = benzoylacetonato), [Ni(dbm) 2] (dbm = dibenzoylmethanato), [Ni(dpm) 2] (dpm = dipavaloylmethanato) are found to be reactive towards C 2N 2 to give selectively square-planar complexes of stoichiometry [Ni(ligand·C 2N 2) 2]. The reaction of [Ni(acac) 2] with C 2N 2 was re-considered and the nature of two supposed isomeric products has been thoroughly reinvestigated by a variety of physico-chemical methods, including a combination of thermogravimetry-differential thermal analyses. The complex [Niβ 2] (β = 1-cyano-2-(1-iminoethyl)butane-1,3-dionate) reacts quantitatively with [PdCl 2(PhCN) 2] to give a coordination polymer of approximate composition [(PdCl 2)(Niβ 2) 0.25]. © 1984
- …
