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Unsymmetrical Biaryls by Palladium‐Catalyzed Coupling of Aryl Halides with Internal Reduction
Author(s) -
Satyanarayana Gedu,
Maier Martin E.
Publication year - 2008
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.200800724
Subject(s) - chemistry , aryl , reductive elimination , aryl halide , palladium , transmetalation , enamine , medicinal chemistry , substituent , bromobenzene , allylic rearrangement , heck reaction , benzylamine , organic chemistry , catalysis , alkyl
Aryl bromides containing a (1,4,5,6‐tetrahydro‐6‐oxopyridin‐3‐yl)methyl substituent can be coupled with aryl halides yielding unsummetrical biaryls. In the course of this process, the cyclic enamide is oxidized to the 2(1 H )‐pyridinone. The reaction proceeds by a six‐membered palladacycle resulting from allylic C–H bond activation of the cyclic enamide, leading to a six‐membered palladacycle. A subsequent transmetalation reaction with an aryl‐Pd‐X intermediate eventually leads to mixed biaryls by reductive elimination and β‐hydride elimination. The best yields were obtained with 2 equiv. of aryl halide. The required substrates were prepared from bromoiodobenzenes by a sequence consisting of a Heck reaction with allyl alcohol, enamine formation, Michael addition to ethyl acrylate, and heterocycle formation with benzylamine.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)