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Second Comes First: Switching Elementary Steps in Palladium‐Catalyzed Cross‐Coupling Reactions
Author(s) -
Kolter Marlene,
Koszinowski Konrad
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001041
Subject(s) - transmetalation , chemistry , palladium , reductive elimination , phosphine , oxidative addition , catalysis , reagent , catalytic cycle , coupling reaction , medicinal chemistry , ligand (biochemistry) , alkyl , trifluoromethyl , electrophile , photochemistry , combinatorial chemistry , organic chemistry , biochemistry , receptor
Abstract The electron‐poor palladium(0) complex L 3 Pd (L=tris[3,5‐bis(trifluoromethyl)phenyl]phosphine) reacts with Grignard reagents RMgX and organolithium compounds RLi via transmetalation to furnish the anionic organopalladates [L 2 PdR] − , as shown by negative‐ion mode electrospray‐ionization mass spectrometry. These palladates undergo oxidative additions of organyl halides R′X (or related S N 2‐type reactions) followed by further transmetalation. Gas‐phase fragmentation of the resulting heteroleptic palladate(II) complexes results in the reductive elimination of the cross‐coupling products RR′. This reaction sequence corresponds to a catalytic cycle, in which the order of the elementary steps of transmetalation and oxidative addition is switched relative to that of palladium‐catalyzed cross‐coupling reactions proceeding via neutral intermediates. An attractive feature of the palladate‐based catalytic system is its ability to mediate challenging alkyl–alkyl coupling reactions. However, the poor stability of the phosphine ligand L against decomposition reactions has so far prevented its successful use in practical applications.