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A Pyridine–Pyridine Cross‐Coupling Reaction via Dearomatized Radical Intermediates
Author(s) -
Koniarczyk J. Luke,
Greenwood Jacob W.,
AlegreRequena Juan V.,
Paton Robert S.,
McNally Andrew
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201906267
Subject(s) - chemistry , phosphonium , pyridine , reagent , photochemistry , radical , coupling reaction , radical ion , medicinal chemistry , organic chemistry , catalysis , ion
A pyridine–pyridine coupling reaction has been developed between pyridyl phosphonium salts and cyanopyridines using B 2 pin 2 as an electron‐transfer reagent. Complete regio‐ and cross‐selectivity are observed when forming a range of valuable 2,4′‐bipyridines. Phosphonium salts were found to be the only viable radical precursors in this process, and mechanistic studies indicate that the process does not proceed through a Minisci‐type coupling involving a pyridyl radical. Instead, a radical–radical coupling process between a boryl phosphonium pyridyl radical and a boryl‐stabilized cyanopyridine radical explains the C−C bond‐forming step.