Oxidative nitrene transfer from azides to alkynes <i>via</i> Ti(<scp>ii</scp>)/Ti(<scp>iv</scp>) redox catalysis: formal [2+2+1] synthesis of pyrroles
作者:Adam J. Pearce、Xin Yi See、Ian A. Tonks
DOI:10.1039/c8cc02623h
日期:——
Catalytic oxidative nitrene transfer from azides with the early transition metals is rare, and has not been observed without the support of redox noninnocent spectator ligands.
Low-Valent Niobium-Catalyzed Intermolecular [2 + 2 + 2] Cycloaddition of <i>tert</i>-Butylacetylene and Arylnitriles to Form 2,3,6-Trisubstituted Pyridine Derivatives
作者:Yasushi Satoh、Yasushi Obora
DOI:10.1021/jo401399y
日期:2013.8.2
A catalytic system based on low-valent niobium has been developed, consisting of NbCl5, Zn, and an alkoxysilane. This combination has been shown to be an efficient catalyst for the synthesis of pyridine derivatives from the intermolecular cycloaddition of alkynes and nitriles via a niobacyclopentadiene intermediate.
Substituted benzocyclobutenes, indans, and tetralins via cobalt-catalyzed cooligomerization of .alpha.,.omega.-diynes with substituted acetylenes. Formation and synthetic utility of trimethylsilylated benzocycloalkenes
作者:R. L. Hillard、K. Peter C. Vollhardt
DOI:10.1021/ja00454a026
日期:1977.6
Ruthenium-mediated cyclotrimerization of alkynes utilizing the cationic complex [RuCp(CH3CN)3]PF6
作者:Eva Rüba、Roland Schmid、Karl Kirchner、Maria José Calhorda
DOI:10.1016/s0022-328x(03)00783-6
日期:2003.10
The substitutionally labile cationic complex [RuCp(CH3CN)(3)](+) (as the PF6- salt) was tested with respect to its ability to catalyze the cyclotrimerization of terminal alkynes and diynes to afford benzene derivatives. Whereas [RuCp(CH3CN)(3)](+) is in fact promoting the catalytic cyclotrimerization of alkynes, the formation of stable and inert sandwich complexes of the type [RuCp(eta(6)- arene)](+) deactivates the catalyst and thus quenches the catalytic cycle. All new sandwich complexes were isolated and characterized spectroscopically. A proposal for a plausible catalytic cycle including possible degradation pathways of the catalyst is presented based on DFT calculations. As key intermediates several novel carbene complexes have been identified including metallacyclo-pentatriene and metallaheptatetraene species. (C) 2003 Elsevier B.V. All rights reserved.
579. Poly-cyclotrimerisation of alkadiynes and cycloalkadiynes on complex metal catalysts