Ruthenium-Catalyzed Rearrangement of cis-1-Ethynyl-2-vinyloxiranes to Substituted Phenols

Catalytic cyclization of cis-1-ethynyl-2-vinyloxiranes was implemented with TpRuPPh3 (CH3CN)2PF6 catalyst (10 mol%), to give 2,6-disubstituted phenols in reasonable yields. Under similar conditions, 1,1,2,2-tetrasubstituted oxirane gave the 2,3,6-trisubstituted phenol with skeleton reorganization. On the basis of 2H- and 13C-labeling results, we propose that the reaction mechanism involves electrocyclization of ruthenium-vinylidene intermediate with cleavage of the carbon-oxygen bond of the epoxide.