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The Design and Synthesis of Bis(thiourea) Ligands and Their Application in Pd‐Catalyzed Heck and Suzuki Reactions Under Aerobic Conditions
Author(s) -
Chen Wei,
Li Rui,
Han Bo,
Li BangJing,
Chen YingChun,
Wu Yong,
Ding LiSheng,
Yang Dan
Publication year - 2006
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.200500644
Subject(s) - thiourea , chemistry , catalysis , aryl , palladium , bromide , heck reaction , suzuki reaction , organic chemistry , medicinal chemistry , coupling reaction , chelation , combinatorial chemistry , polymer chemistry , alkyl
New, bulky N , N ‐disubstituted acyclic and cyclic bis(thiourea) ligands have been designed and synthesized. Their palladium(0) complexes are very stable and are active catalysts for Heck and Suzuki coupling reactions of aryl iodides and bromides under aerobic conditions. Good TONs and TOFs were achieved in the coupling reactions [for PhI, TONs up to 1 and TOFs up to 2 (h –1 ); for activated aryl bromide, TONs up to 89000]. In addition, further studies were conducted to know more about the nature of these catalysts. The active catalyst was found to be the chelate complex containing the bis(thiourea) and Pd in a 1:1 ratio. However, unlike a monothiourea, further coordination can occur to give a coordinatively saturated complex when bis(thiourea) and Pd are combined in a 2:1 ratio; this complex is catalytically inactive in coupling reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)