Y. Makioka et al., ISOMERIZATION OF TERMINAL ALKYNES CATALYZED BY YTTERBIUM(II)-AROMATICIMINE COMPLEXES, Bulletin de la Societe chimique de France, 134(3-4), 1997, pp. 349-355
Ytterbium-aromatic imine dianion complexes 2, wich can easily be prepa
red from metallic ytterbium and aromatic imines 1, can act as effectiv
e catalysts for the isomerization of terminal alkynes 3 under mild con
ditions to afford internal alk-2-ynes 4 in good yields. In the reactio
n of 1-hexyne 3a, 2-hexyne 4a can be simply obtained by trap-to-trap d
istillation and the catalytic system can be reused for the isomerizati
on of 3a without other treatments.