A highly efficient Pd(OAc)2/guanidine aqueous system for the room temperature Suzuki cross-coupling reaction has been developed. The new water-soluble and air-stable catalyst Pd(OAc)2.(1f)2 from Pd(OAc)2 and 1,1,3,3-tetramethyl-2-n-butylguanidine (1f) was synthesized and characterized by X-ray crystallography. In the presence of Pd(OAc)2.(1f)2, coupling of arylboronic acids with a wide range of aryl halides, including aryl iodides, aryl bromides, even activated aryl chlorides, was carried out smoothly in aqueous solvent to afford the cross-coupling products in good to excellent yields and high turnover numbers (TONs) (TONs up to 850,000 for the reaction of 1-iodo-4-nitrobenzene and phenylboronic acid). Furthermore, this mild protocol could tolerate a broad range of functional groups.
[reaction: see text]. Brønsted acid-base ionic liquids (GILs) based on guanidine and acetic acid are efficient reaction media for palladium-catalyzed Heck reactions. They offer the advantages of high activity and reusability. GIL2 plays multiple roles in the reaction: it could act as solvent, as a strong base to facilitate beta-hydride elimination, and as a ligand to stabilize activated Pd species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.