Low-valent cobalt complexes in C-X coupling and related reactions

Economical and eco-compatible catalytic systems are essential for carbon-carbon and carbon-heteroatom bond formation involving cross-coupling reactions. Among them, cobalt-catalysed protocols allow a wide range of functional groups and offer an excellent alternative to usual catalysts such as palladium and nickel. Different cobalt-catalysed carbon-carbon bond formations have already been reported either from various stoichiometric organometallic species or by reductive cross-coupling reactions. Although several organometallic species can be used for cobalt-catalysed cross-coupling reactions, Grignard and organozinc reagents are mainly employed. However, the advantage of developing new reductive cross-couplings directly from two electrophiles avoids the preparation of stoichiometric organometallic reagents. This chapter deals with these different cobalt-catalysed cross-coupling reactions.