Three newpalladium catalysts, prepared via reactions of PdCl2 with readily obtained and inexpensive dicationic imidazolium salts, have been developed for the Suzuki reaction. The pre-catalyst was formed in situ using the imidazolium ligand, base and Pd metal precursor in 1,4-dioxane. This palladium catalyst provides a convenient and general method for the synthesis of biaryls from aryl bromides, activated
The immobilisation of an oxime-based palladacycle on polyvinylpyridine (PVP) resin affords a reusable, air, moisture and thermally stable palladium precatalyst which exerts high activity in Suzuki-Miyaura reactions both in batch as well as continuous-flow processes. Evidence is presented which shows that, besides serving as an anchor for the precatalyst, PVP also acts as a scavenger for Pd particles present in solution.
Combining enabling techniques in organic synthesis: solid-phase-assisted catalysis under microwave conditions using a stable Pd(II)-precatalyst
作者:Kamal M. Dawood、Andreas Kirschning
DOI:10.1016/j.tet.2005.07.113
日期:2005.12
2-pyridinealdoxime-based Pd(II)-complex covalently anchored via the oxime moiety to a glass/polymer composite material was evaluated in Suzuki–Miyaura cross-coupling reactions of aryl and heteroaryl halides, including arylchlorides, with aryl and heteroaryl boronic acids both under thermal as well as microwaveirradiatingconditions in water. The stability and reusability of this Pd-precatalyst is part
as Raschig rings or placed within the PASSflow TM microreactor affords technical devices that are well suited for performing palladium-catalyzed carbon-carbon cross-couplingreactions in the flow-through mode. Reusability of the immobilized precatalyst as well as applications in the microwave field were investigated. Experiments with thiol- and pyridine-based scavengers were carried out, which revealed