Prominent Ligand Types in Modern Cross-Coupling Reactions - New Trends in Cross-Coupling: Theory and Applications - page 20

CHAPTER 2
Prominent Ligand Types in
Modern Cross-Coupling
Reactions
ANDREW DEANGELIS AND THOMAS J. COLACOT*
Johnson Matthey Catalysis and Chiral Technologies, 2001 Nolte Drive,
West Deptford, NJ 08066, USA
*Email: [e-mail]
2.1 Introduction
Intense research efforts have been ongoing in the area of ligand develop-
ment since the late 1990s, which significantly accelerated the advancement
of Pd-catalyzed cross-coupling to reach the premium status that it has
achieved today. Several excellent reviews 1 and topics 2 encompass the
historical perspectives of the development of the state-of-the-art technology
in cross-coupling, wherein the importance of ligands has been highlighted.
Although cross-coupling emerged in large part from Glaser's seminal work
in the 1800s for copper-mediated processes, such as alkyne dimerization, 3
followed by the use of Ni-, Fe- and Co-based catalysts, 2a palladium has be-
come the metal of choice in the majority of cross-coupling reactions as it has
proven to be unparalleled in terms of reaction scope and functional group
compatibility. The reactive intermediates formed along the catalytic cycle
feature an excellent balance of reactivity and stability when palladium is
employed relative to other metals. Furthermore, phosphine ligands have
become the ligands of choice in conjunction with Pd owing to their high
activity, ease of synthesis and fine tuning, although many useful catalyst