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Chemoselective Suzuki Coupling of Bromoarenes Catalysed by Palladium(II)‐Complexing Macrocycles in Aqueous Media
Author(s) -
Ogawa Masahiro,
Sogawa Hiromitsu,
Mizuno Shunya,
Aoki Daisuke,
Takata Toshikazu
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201703073
Subject(s) - chemoselectivity , palladium , chemistry , suzuki reaction , aryl , catalysis , ligand (biochemistry) , chloride , combinatorial chemistry , yield (engineering) , organic chemistry , alkyl , materials science , biochemistry , receptor , metallurgy
Abstract Palladium‐complexing macrocyclic catalysts efficiently and chemoselectively catalysed the Suzuki coupling reaction of bromoarenes. Bromobenzene and 2‐bromopyridine were efficiently monoarylated with 4‐methoxyphenylboronic acid when catalysed by macrocyclic catalysts comprising cyclic pyridine‐2,6‐bisamide pincer‐type ligands with palladium (II) located in the inner cavity (PdMCs). The Suzuki coupling of 2,6‐dibromopyridine to aryl boronic acids catalysed by PdMCs afforded the corresponding monoarylpyridines with high selectivity and yield, whereas a mixture of mono‐ and di‐arylpyridines was obtained when palladium chloride was used as the catalyst. Interestingly, the chemoselectivity increased as the cavity size of the PdMCs decreased. The high chemoselectivity seemed to arise from the steric effect of the macrocyclic ligand. Moreover, an unsymmetrical 2,6‐diarylpyridine was successfully synthesised in high yield by two sequential couplings employing PdMCs followed by palladium chloride.