Solvent-dependent chemoselectivity in ruthenium-catalyzed cyclization of iodoalkyne-epoxide functionalities.
[reaction: see text] Treatment of 1-(2'-iodoethynylphenyl)-2-propyloxirane (3) with TpRuPPh(3)(CH(3)CN)(2)PF(6) catalyst (10 mol %) produced 1-iodo-2-naphthol (3a) exclusively in DMF, but gave 2-iodobenzo[d]oxepin (3b) efficiently in benzene. Such a solvent-dependent chemoselectivity suggests a solution equilibrium between ruthenium-pi-iodoalkyne and ruthenium-2-iodovinylidene intermediates.
Lin
Ming-Yuan
MY
Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan 30043, Republic of China.
Maddirala
Shambabu Joseph
SJ
Liu
Rai-Shung
RS