Cobalt-Mediated Vinylic C-H Functionalization of Alkenes

The reaction of cobalt dinitrosyl complexes with alkenes to form cobalt dinitrosoalkane complexes is used to effect the C-H functionalization of alkenes. Deprotonation of cobalt dinitrosoalkane complexes, followed by reaction with neutral electrophiles, yields functionalized cobalt complexes. Thermolysis of such complexes with the parent alkene allows a migration of the cobalt dinitrosyl moiety to the parent alkene, releasing the organic product of C-H functionalization. Progress is presented towards rendering this sequence of reactions catalytic in cobalt. Additionally, the use of reagents derived from Cinchona alkaloids allows for this functionalization to be rendered enantioselective. The enantioselective chemistry has been utilized in the synthesis of chiral diene ligands for rhodium-catalyzed conjugate addition reactions. The use of hydridotris(pyrazolyl)borates, in place of cyclopentadienyls, as spectator ligands for cobalt dinitrosoalkane complexes, is also explored, and the electronic structure of a cobalt mononitrosyl complex studied