ISOMERIZATION OF TERMINAL ALKYNES CATALYZED BY YTTERBIUM(II)-AROMATICIMINE COMPLEXES

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.