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High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview
Author(s) -
Farina Vittorio
Publication year - 2004
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404178
Subject(s) - catalysis , chemistry , palladium , denticity , carbene , heck reaction , organometallic chemistry , combinatorial chemistry , ligand (biochemistry) , scope (computer science) , coupling reaction , organic chemistry , metal , biochemistry , receptor , computer science , programming language
This review discusses the problems associated with developing high‐turnover catalysts for the cross‐coupling and Heck reactions. New developments in the area, principally constituted by palladacycles and coordinatively unsaturated Pd catalysts featuring bulky phosphanes of high donicity, are reviewed from a mechanistic and synthetic standpoint, and compared with more traditional catalysts obtained from conventional mono‐ and polydentate N‐ and P‐based ligands, as well as Pd catalysts without strong ligands, such as Pd colloids or heterogeneous catalysts. Carbene ligands are also briefly presented. Whereas a single, most promising approach to high‐turnover Pd catalysis cannot presently be defined, it is clear that the new “PdL 1 ” catalysts (where L 1 is a monodentate bulky P ligand of high donicity) represent the latest, most important development in Pd research, certainly from the standpoint of scope and probably also from the standpoint of efficiency. High turnovers with these catalysts have been described and their use will certainly increase in the next few years. The review ends with a brief discussion containing practical considerations on how to choose a high TON catalyst for a given Heck or cross‐coupling reaction of interest.