828-13-7Relevant articles and documents
Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
Liu, Bingxue,Liu, Qiang,Liu, Xufang
supporting information, p. 6750 - 6755 (2020/03/13)
Migratory functionalization of alkenes has emerged as a powerful strategy to achieve functionalization at a distal position to the original reactive site on a hydrocarbon chain. However, an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminal alkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminal alkynes and cobalt-catalyzed hydrogenation of either 2-alkynes or conjugated diene intermediates. Notably, this practical non-noble metal catalytic system enables efficient control of the chemo-, regio-, and stereoselectivity of this transformation.
Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
, p. 5723 - 5728 (2019/04/03)
We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
An N-heterocyclic carbene ligand promotes highly selective alkyne semihydrogenation with copper nanoparticles supported on passivated silica
Kaeffer, Nicolas,Liu, Hsueh-Ju,Lo, Hung-Kun,Fedorov, Alexey,Copéret, Christophe
, p. 5366 - 5371 (2018/06/27)
We report a surface organometallic route that generates copper nanoparticles (NPs) on a silica support while simultaneously passivating the silica surface with trimethylsiloxy groups. The material is active for the catalytic semihydrogenation of phenylalkyl-, dialkyl- and diaryl-alkynes and displays high chemo- and stereoselectivity at full alkyne conversion to corresponding (Z)-olefins in the presence of an N-heterocyclic carbene (NHC) ligand. Solid-state NMR spectroscopy using the NHC ligand 13C-labeled at the carbenic carbon reveals a genuine coordination of the carbene to Cu NPs. The presence of distinct Cu surface environments and the coordination of the NHC to specific Cu sites likely account for the increased selectivity.
Intramolecular Photocycloaddition of 3-Benzyloxyprop-1-enes
Blakemore, David D.,Gilbert, Andrew
, p. 2265 - 2270 (2007/10/02)
The photochemistry of 3-benzyloxyprop-1-ene is markedly influenced by the presence of features which direct the intramolecular meta photocycloaddition to the 1,3-positions of the benzene ring and by constraining the benzylic position in the bichromophore.Thus, derivatives having 2'-methyl, 2'-methoxy and/or 1,1-dimethyl substitution yield meta photocycloadducts with the isomer having the linear triquinane unit greatly predominating.Adducts arising from 1,2-intramolecular attack are also observed from the substituted 3-benzyloxyprop-1-enes but the major by-product from 1-benzyloxy-3-methylbut-2-ene is the novel spiro compound 28 derived from an "ene" type reaction.The indanyl vinyl ethers undergo meta photocycloaddition to give both the bridged linear and angular triquinane skeleta with the former again predominating, while for the corresponding unsubstituted tetralin derivative the angular isomer is formed in the greater yield and with the dimethyl compound 36, the major photoisomer results from an initial intramolecular 1,2-attack in the bichromophore followed by thermal ring opening and 4?-photocyclisation.
A CONVENIENT COUPLING REACTION OF ALLYL ALCOHOLS WITH GRIGNARD REAGENTS USING 1-CHLORO-2-METHYL-N,N-TETRAMETHYLENEPROPENYLAMINE
Fujisawa, Tamotsu,Iida, Sachio,Yukizaki, Hisashi,Sato, Toshio
, p. 5745 - 5748 (2007/10/02)
1-Chloro-2-methyl-N,N-tetramethylenepropenylamine was found to be a good condensation reagent for a regioselective coupling reaction of allyl alcohols with Grignard reagents under mild conditions to afford olefinic products.
