2809-67-8Relevant articles and documents
Ytterbium(II)-aromatic imine dianion complexes-catalyzed isomerization of terminal alkynes
Makioka, Yoshikazu,Saiki, Akira,Takaki, Ken,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo
, p. 27 - 28 (1997)
Ytterbium-aromatic imine dianion complexes, easily prepared from ytterbium metal and aromatic imines, can act as effective catalysts for the isomerization of terminal alkynes to afford internal alkynes in good to high yields.
Unprecedented Spectroscopic and Computational Evidence for Allenyl and Propargyl Titanocene(IV) Complexes: Electrophilic Quenching of Their Metallotropic Equilibrium
Ruiz-Muelle, Ana Belén,O?a-Burgos, Pascual,Ortu?o, Manuel A.,Oltra, J. Enrique,Rodríguez-García, Ignacio,Fernández, Ignacio
, p. 2427 - 2439 (2016/02/14)
The synthesis and structural characterization of allenyl titanocene(IV) [TiClCp2(CH=C=CH2)] 3 and propargyl titanocene(IV) [TiClCp2(CH2-C≡C-(CH2)4CH3)] 9 have been described for the first time. Advanced NMR methods including diffusion NMR methods (diffusion pulsed field gradient stimulated spin echo (PFG-STE) and DOSY) have been applied and established that these organometallics are monomers in THF solution with hydrodynamic radii (from the Stokes-Einstein equation) of 3.5 and 4.1 ? for 3 and 9, respectively. Full 1H, 13C, Δ1H, and Δ13C NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights into these derivatives are provided. In solution, they are involved in their respective metallotropic allenyl-propargyl equilibria that, after quenching experiments with aromatic and aliphatic aldehydes, ketones, and protonating agents, always give the propargyl products P (when carbonyls are employed), or allenyl products A (when a proton source is added) as the major isomers. In all the cases assayed, the ratio of products suggests that the metallotropic equilibrium should be faster than the reactions of 3 and 9 with electrophiles. Indeed, DFT calculations predict lower Gibbs energy barriers for the metallotropic equilibrium, thus confirming dynamic kinetic resolution.
Isomerization of terminal alkynes catalyzed by itterbium(II)-aromatic imine complexes
Makioka, Yoshikazu,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo,Saiki, Akira,Takaki, Ken
, p. 349 - 356 (2007/10/03)
Ytterbium-aromatic imine dianion complexes 2, which can easily be prepared from metallic ytterbium and aromatic imines 1, can act as effective catalysts for the isomerization of terminal alkynes 3 under mild conditions to afford internal alk-2-ynes 4 in good yields.In the reaction of 1-hexene 3a, 2-hexyne 3a, 2-hexyne 4a can be simply obtained by trap-to-trap distillation and the catalytic system can be reused for the isomerization of 3a without other treatments. - Keywords: lanthanoid-imine complex; terminal alkyne; isomerization; alk-2-yne