67530-99-8Relevant academic research and scientific papers
Solvent-free synthesis of 2-pyrones from alkynes and carbon dioxide catalyzed by Ni(1,5-cyclooctadiene)2/trialkylphosphine catalysts
Kishimoto, Yasuhisa,Mitani, Ikuko
, p. 2141 - 2146 (2007/10/03)
Solvent-free, efficient, and mild 2-pyrone synthesis by the cycloaddition of alkynes with CO2 has been achieved under compressed CO2 with a Ni(cod)2/P(C4H9)3 or Ni(cod)2/P(C8H17)3 catalyst; both high yields (up to 98%) and selectivities (up to 99%) are attained. One attractive aspect of these catalysts is their high efficiency at low CO 2 pressures (4 MPa). The applicability of this reaction to a broad range of alkyne substrates and the ease of handling the phosphine ligands are additional merits of the present new catalytic systems in comparison to the previously reported Ni(cod)2/P(CH3)3 catalyst in supercritical CO2. Georg Thieme Verlag Stuttgart.
Aktivierung von Kohlendioxid an Uebergangsmetallzentren: Selektive Cooligomerisation mit Hexin(-3) durch das Katalysatorsystem Acetonitril/Trialkylphosphan/Nickel(0) und Struktur eines Nickel(0)-Komplexes mit side-on gebundenem Acetonitril
Walther, Dirk,Schoenberg, Hartmut,Dinjus, Eckard,Sieler, Joachim
, p. 377 - 388 (2007/10/02)
CO2 reacts with hexyne(-3) in a catalytic reaction under formation of tetraethyl-2-pyrone, when the catalytic system alkyl3P/acetonitrile/nickel(0) is used.The selectivity of this homogeneous-catalytic reaction can be increased to values of 96percent when phosphanes of high basicity and small cone angle are used.The investigation of the system Ni(COD)2/tricyclohexylphosphane/acetonitrile shows that acetonitrile can act as ligand in complexes of nickel(0).A yellow-brown tetranuclear complex was isolated, the structure of which was determined by X-ray diffraction studies.Acetonitrile acts as bridging ligand and is coordinated alkyne-analogously to one nickel center with its triple bond.The free electron pair of the nitrogen atom is bonded to a second nickel atom.Some reaction steps of this selective catalytic reaction are discussed.This reaction represents the first example of a selective homogeneous-catalytic co-oligomerization between CO2 and an unsaturated substrate which takes place under C-C linkage with a 3d-transition metal.
Reaction of Dialkyl-substituted Alkynes with Carbon Dioxide Catalyzed by Nickel(0) Complexes. Incorporation of Carbon Dioxide in Alkyne Dimers and Novel Cyclotrimerization of the Alkynes
Inoue, Yoshio,Itoh, Yoshio,Kazama, Haruo,Hashimoto, Harukichi
, p. 3329 - 3333 (2007/10/02)
Ni(cod)2-Ph2P(CH2)4PPh2 system (cod=1,5-cyclooctadiene) catalyzed the reaction of 3-hexyne, for example, with CO2 to give a CO2 incorporated product, i.e., tetraethyl-2-pyrone, in a fairly good yield together with novel two cyclotrimers of the alkyne having cyclopentadiene structures, i.e., pentaethyl-5-(1-propenyl)-1,3-cyclopentadiene and pentaethyl-5-allyl-1,3-cyclopentadiene.The novel two cyclotrimers were formed selectively on Ni(cod)2-PPh3 system under CO2, whereas under N2 the main trimer was hexaethylbenzene.A nickelacyclopentadiene intermediate has been proposed for the pyrone formation.The novel two cyclotrimers were also formed on the oligomerization catalyzed by a cationic nickel hydride complex, OCOCF3, together with a novel dimer having a methylenecyclobutane structure, i.e., 1,2,4-triethyl-3-ethylidenecyclobutene.The effect of posphine added and that of active-hydrogen compounds on the novel oligomerization are mentioned.
