Radical coupling reactions of 1,3- and 1,4-enynes were studied with the dinuclear cobalt core acting as a stabilizing and stereodirecting moiety. The complementary methods for the generation of requisite cations � alpha- and gamma- to a metal core � were developed employing either cation isolation procedure with tetrafluoroboric acid, or in situ generation of ionic propargyl triflates with triflic anhydride. Independent of the topology, substrate alcohols and methyl ethers exclusively couple at gamma positions giving rise to tail-to-tail radical dimers with vicinally disposed quaternary carbon centers (98-99%). The scope of the reaction was expanded to involve cobalt enyne complexes with aliphatic and aromatic substituents at acetylenic termini, or gamma to a metal core. The level of diastereoselection was dependent upon the substitution pattern and electronic nature of the substituents. The X-ray crystallographic data will be presented along with the computational studies on intermediate cations and radicals.

Allylic rearrangements in cobalt-mediated radical coupling reactions

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.