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Pd‐PEPPSI Complexes and the Negishi Reaction
Author(s) -
Valente Cory,
Belowich Matthew E.,
Hadei Niloufar,
Organ Michael G.
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201000359
Subject(s) - negishi coupling , chemistry , steric effects , combinatorial chemistry , catalysis , organic chemistry
An overview of Pd‐PEPPSI complexes in the Negishi cross‐coupling reaction is presented. Preliminary evaluations of differentially substituted imidazolium salts that generate highly active cross‐coupling catalysts in situ provide the foundation for the development of an air‐ and moisture‐stable NHC‐based precatalyst: Pd‐PEPPSI‐IPr. The application of Pd‐PEPPSI‐IPr in sp 3 –sp 3 , sp 3 –sp 2 (and vice versa), and sp 2 –sp 2 Negishi cross‐couplings is reviewed. This allowed the systematic development of Pd‐PEPPSI‐IPent, a more sterically demanding, second‐generation catalyst that outperforms the IPr analogue in a variety of sp 2 –sp 2 Negishi cross‐couplings. General routes for the preparation of organozinc reagents are also examined, and an additives study reveals the probable transmetallating species that is operative in these cross‐couplings. Mechanistic considerations of the Negishi cross‐coupling reaction based on experimental and computational studies are summarized and evaluated.