Open AccessPd-Catalyzed Aerobic Oxidative Coupling of Thiophenes: Synergistic Benefits of Phenanthroline Dione and a Cu Cocatalyst
Author(s) -
Stephen J. Tereniak,
David L. Bruns,
Shan S. Stahl
Publication year - 2020
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.0c09962
Subject(s) - chemistry , catalysis , oxidative phosphorylation , phenanthroline , oxidative coupling of methane , ligand (biochemistry) , combinatorial chemistry , coupling (piping) , photochemistry , medicinal chemistry , organic chemistry , biochemistry , receptor , metallurgy , materials science
Substituted bithiophenes are prominent fragments in functional organic materials, and they are ideally prepared via direct oxidative C-H/C-H coupling. Here, we report a novel Pd II catalyst system, employing 1,10-phenanthroline-5,6-dione (phd) as the ancillary ligand, that enables aerobic oxidative homocoupling of 2-bromothiophenes and other related heterocycles. These observations represent the first use of phd to support Pd-catalyzed aerobic oxidation. The reaction also benefits from a Cu(OAc) 2 cocatalyst, and mechanistic studies show that Cu promotes C-C coupling, implicating a role for Cu II different from its conventional contribution to reoxidation of the Pd catalyst.