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A Combined Experimental/Computational Study of the Mechanism of a Palladium‐Catalyzed Bora‐Negishi Reaction
Author(s) -
Campos Jesús,
Nova Ainara,
Kolychev Eugene L.,
Aldridge Simon
Publication year - 2017
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.201702703
Subject(s) - negishi coupling , catalysis , palladium , chemistry , nucleophile , combinatorial chemistry , reagent , aryl , boron , organic chemistry , alkyl
Experimental and computational efforts are reported which illuminate the mechanism of a novel boron version of the widespread Negishi coupling reaction that offers a new protocol for the formation of aryl/acyl C−B bonds using a bulky boryl fragment. The role of nucleophilic borylzinc reagents in the reduction of the Pd II pre‐catalysts to Pd 0 active species has been demonstrated. The non‐innocent behavior of the PPh 3 ligands of the [Pd(PPh 3 ) 2 Cl 2 ] pre‐catalyst under activation conditions has been probed both experimentally and computationally, revealing the formation of a trimetallic Pd species bearing bridging phosphide (PPh 2 − ) ligands. Our studies also reveal the monoligated formulation of the Pd 0 active species, which led us to synthesize related (η 3 ‐indenyl)Pd‐monophosphine catalysts which show improved catalytic performances under mild conditions. A complete mechanistic proposal to aid future catalyst developments is provided.