Diastereoselective formation of 5-vinylcyclopentenes from 1, 6-enynes: cobalt-mediated C-H allylic activation and formal 5-endo-Dig cyclization
A novel intramolecular cyclization reaction mediated by dicobalt octacarbonyl (Co(2)(CO)(8)) is reported. Thermolysis in an argon atmosphere transforms the cobalt complex of 1-trimethylsilyl-6-hepten-1-ynes into 1-trimethylsilyl-5-vinylcyclopentenes in good yield and in a highly diastereoselective manner. This formal 5-endo-dig cyclization is proposed to proceed via an allylic C-H oxidative addition.
Dolaine
R
Department of Chemistry, McGill University, 801 Sherbroke St. West, Montreal, Quebec H3A 2K6, Canada.
Gleason
JL