Chemoselective Cobalt(I)-Catalyzed Cyclotrimerization of (Un)Symmetrical 1,3-Butadiynes for the Synthesis of 1,2,4-Regioisomers
作者:Sebastian M. Weber、Gerhard Hilt
DOI:10.1021/acs.orglett.9b01281
日期:2019.6.7
The cobalt(I)-catalyzed cyclotrimerization of (un)symmetrical 1,4-disubstituted 1,3-butadiynes is presented. In the case of unsymmetrical 1,3-butadiynes, this reaction can generate eight 1,2,4-substituted and four 1,3,5-substituted isomers. A single 1,2,4-substituted isomer was formed in excellent yields (up to 99%) and exclusive regioselectivities (>99:1) when symmetrical or a 1,3-butadiyne with an
Rhodium-catalyzed electrochemical [2 + 2 + 2] cyclotrimerization of 1,3-butadiynes toward hexasubstituted arenes
作者:Mu-Jia Luo、Gui-Fen Lv、Jing-Hao Qin、Chong-Hui Xu、Yang Li、Jin-Heng Li
DOI:10.1039/d3gc02831c
日期:——
attractive method for the construction of diverse organic frameworks because it obviates the use of chemical redox reagents. Herein, we report an elegant rhodium-catalyzed electrochemical [2 + 2 + 2] cyclotrimerization of 1,3-butadiynes for the regioselective synthesis of structurally diverse hexasubstituted arenes in an undivided cell. This methodology features excellent regioselectivity, good functional
In the present work, we demonstrate a regioselective [2 + 2 + 2] cyclotrimerization of 1,3-diynes catalyzed by Ni0 to provide hexasubstituted benzenes (HSBs). HSBs have significant applications as functional materials and pharmaceuticals. The present protocol exhibited remarkable versatility, transforming 1,3-diynes with diverse alkyl, aryl, and heterocyclic groups to the corresponding HSBs. With the
The hydrosilatation of Pr-n-C=C-Pr-n, Ph-C=C-Ph, Me3Si-C=C-SiMe3, Ph-C=C-C=C-Ph, Bu-t-C=C-C=C-Bu-t and Me3Si-C=C-C=C-SiMe3 with Ph2SiH2, PhMe2SiH and Et3SiH in the presence of L2Ni(0)-butadiyne catalysts [L = Ph3P, (o-Tol-O)(3)P] has been studied. In all cases the hydrosilylation proceeds via a cis-addition of the silanes. The disubstituted alkynes (Pr-n-C=C-Pr-n, Ph-C=C-Ph) give hydrosilylated ethene, butadiene and hexatriene derivatives as well as non-hydrosilylated benzene derivatives. In the case of Me3Si-C=C-SiMe3 no reaction was observed. The hydrosilylation of disubstituted butadiynes proceeds stepwise to give at first the 1,2-adducts. In dependence on the butadiynes either a 1,4-addition (Bu-t-C=C-C=C-Bu-t, Me3Si-C=C-C=C-SiMe3) to the corresponding allene derivatives (11, 13, 15) or a 3,4-addition (Ph-C=C-C=C-Ph) to the 1,3-butadiene 19 takes place subsequently. The reaction products were characterized by mass spectrometry, IR and NMR spectroscopy.