Suzuki-Miyaura reaction is a coupling reaction of an aromatic halide and an aromatic boronic acid. This reaction is catalyzed by palladium in the presence of a base, and conventionally needs a phosphorous-containing ligand for activation of the catalyst. Further, because a bisaryl compound of the product is useful for pharmaceuticals and an organic electronic material, the reaction has been utilized not only for a basic research, but also for industries.
However, because palladium is expensive and its contamination to products is regulated, a novel palladium catalyst which does not cause leakage and can be recycled has been sought. Also a catalyst which has a high catalytic activity and does not require a use of an expensive and toxic phosphorous-containing ligand has been demanded.
As for recycling of a palladium catalyst after the use for reaction, non-patent document 1 discloses that a palladium catalyst supported on a hydroxyapatite has an activity for Suzuki-Miyaura coupling reaction between bromobenzene and phenylboric acid, and has a high turnover number (TON). However, the catalyst has also disadvantages such as slightly low catalytic activity and necessity of a severe condition of reaction as high as 120° C.
Additionally, non-patent document 2 discloses a solid-phase palladium catalyst, using a non-cross-linked amphipathic macromolecule with a ligand of arylphosphine, has an activity for Suzuki-Miyaura reaction and also a high TON. However, as is the case with non-patent document 1, the catalyst requires a severe reaction condition as high as 100° C. Furthermore, the catalyst had another disadvantage that the cost for production of the non-cross-linking amphipathic macromolecule is expensive.
Whilst, the inventors developed a palladium catalyst dissolved in an ionic liquid and supported on a porous carrier (patent document 1), however, it is desirable to provide a more excellent palladium catalyst.
USPTO Backgrounds
USPTO Backgrounds