20826-80-6Relevant articles and documents
Theoretical studies on the addition of polymetallic lithium organocuprate clusters to acetylene. Cooperative effects of metals in a trap-and-bite reaction pathway
Nakamura, Eiichi,Mori, Seiji,Nakamura, Masaharu,Morokuma, Keiji
, p. 4887 - 4899 (1997)
Ab initio and density functional theoretical investigations into the nature of the reaction of acetylene with noncluster organocuprate reagents, MeCu, Me2Cu-, and lithium organocuprate cluster reagents, Me2CuLi, Me2-CuLi·LiCl, and (Me2CuLi)2 were carried out, and the function of the mixed metal cluster was probed. Intermediates transition structures (TSs) as well as the structures on the intrinsic reaction coordinate in the C-C bond forming stage of the reaction of lithium cuprate clusters have been calculated with the ab initio method (MP2) and density functional method (B3LYP) using all-electron basis sets for copper. The addition reaction of the simple organocopper reagent, MeCu, can be viewed as a simple four-centered addition reaction consisting of nucleophilic addition of an anionic methyl group, while the addition of the cuprate reagent, Me2Cu-, involves transfer of negative charge to the acetylene via the copper atom. In the cluster reaction of Me2CuLi·LiC1, the lithium atom in the cluster stabilizes the developing negative charge on the acetylene moiety and assists the electron flow from the copper atom. Reductive elimination of the transient Cu(III) species initially gives a 1- propenyllithuim-like structure intermediate (nonstationary point), which then undergoes intramolecular transmetalation to give the final product. 1-propenylcopper. Essentially the same mechanism operates also with Me2CuLi and (Me2CuLi)2, indicating that the Li-Me-Cu-Me moiety incorporated in the mixed organocuprate cluster is essential for the reaction. Experiments showed that the strong solvation of the lithium atom with a crown ether, which sequesters the lithium cation from the cluster, strongly decelerates the carbocupration reaction. Thus, theory and experiments revealed the cooperative function of lithium and copper atoms in the cuprate reactions.
α-Sulfinyl Carbanions as a New Source of Olefins
Abramovitch, Adi,Varghese, Jos P.,Marek, Ilan
, p. 621 - 623 (2004)
(Matrix presented) Secondary α-lithiosulfinyl carbanions react either intermolecularly, after transmetalation into an organocopper derivative in an SN2-type process with zinc carbenoid, or intramolecularly via higher-order zincate to give, through a tandem zinc homologation-β- elimination reaction the corresponding alkenes. α,α-Disubstituted alkenes are only formed from tertiary α-lithiosulfinyl carbanions via the 1,2-metalate rearrangement.
Visible-Light-Induced Meerwein Fluoroarylation of Styrenes
Tang, Hai-Jun,Zhang, Bin,Xue, Fei,Feng, Chao
supporting information, p. 4040 - 4044 (2021/05/26)
An unprecedented approach for assembling a broad range of 1,2-diarylethane derivatives with fluorine-containing fully substituted carbon centers was developed. The protocol features straightforward operation, proceeds under metal-free condition, and accommodates a large variety of synthetically useful functionalities. The critical aspect to the success of this novel transformation lies in using aryldiazonium salts as both aryl radical progenitor and also as single electron acceptor which elegantly enables a radical-polar crossover manifold.
Recyclable and reusable PdCl2(PPh3)2/PEG-400/H2O system for the hydrophenylation of alkynes with sodium tetraphenylborate
Liu, Rong,Zhang, Tingli,Huang, Bin,Cai, Mingzhong
, p. 172 - 178 (2020/07/04)
A stable and efficient PdCl2(PPh3)2/PEG-400/H2O catalytic system for the hydrophenylation reaction of alkynes has been developed. In the presence of 3 mol% PdCl2(PPh3)2 and 2 equiv. of HOAc, the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate proceeded smoothly in a mixture of PEG-400 and water at room temperature or 50 °C to afford a variety of phenyl-substituted alkenes in moderate to high yields. The isolation of the products was easily performed by extraction with petroleum ether, and the PdCl2(PPh3)2/PEG-400/H2O system could be readily recycled and reused six times without apparent loss of catalytic activity.
