The Suzuki-Miyaura reaction, discovered in 1979, is one of the most useful reactions for the synthesis of molecules which contain aromatic (heterocyclic)-aromatic bonds. A large number of marketed drugs and new drug candidates now contain this biaryl part-structure, and some examples are shown here:

Despite these advances, there were, until recently some issues which needed resolution such as:

1)  the ability to use aryl chlorides or sulfonates routinely

2)  cross coupling of sterically hindered systems

3)  use of components which can undergo competitive b-hydride elimination

4)  effective cross coupling of electron-deficient and heteroaromatic organoboron reagents

The solution for many of these challenges has turned out to reside in the development of effective palladium/ligand catalyst systems and an understanding of the mechanistic aspects of the catalytic cycle.

An excellent review (G.A. Molander and B. Cantrick, Angew Chem Int. Ed, 2009, 48, 9240-9261) discusses these issues and how they affect the choice of substrate (particularly the boron component) and the catalyst and ligand, with emphasis on the use of organotrifluoroborates (both alkyl and aryl) and mono-ligating, electron rich ligands.