Design And Synthesis Of Novel Oxime Phosphine Ligands And Their Applications In Transition-Metal Catalyzed Cross-Coupling Reactions

Selectively catalytic reaction has become a focus of research in organicsynthesis. Derived from readily available o-bromobenzadehyde, two series of newligands, namely, oxime-phosphines (49 and 50) and oxime-phosphine oxides (51and 52) were designed and synthesized. These ligands have been used inpalladium-catalyzed Suzuki-Miyaura reactions and copper-catalyzed C(aryl)-Nbond forming reactions respectively, and both of them show good results.Using palldium catalyst and 49 or 50 as ligand, the Suzuki-Miyaura cross-coupling reaction between 4-bromotoluene and phenylboronic acid could becarried out efficiently and rapidly with almost quantitative yield. Even if theAr₃P-type ligand 49 was used, a variety of arylbromides could be coupled witharylboronic acid successfully with high yields of the relative products underoptimized reaction conditions and TON could up to 10⁴.Using Cu₂O as catalyst, both 51 and 52 showed high catalytic activities in thecross-coupling reaction of iodobenzene with n-hexylamine. Under the optimizedconditions, the reactions between primary alkylamines and aryl iodides could beperformed successfully to afford the products with high yields generally using thenew catalyzed systems based on 51, and many of these transformations are themost efficient up to now. Secondary amines could also be coupled with aryliodides, however, the yields were slightly lower than primary amines. Besidesalkylamines, N-H heterocycles were also suitable substrates. In addition, differentamines could be coupled with aryl iodides successfully with moderate to goodyields in solvent-free conditions. The use of highly efficient and readily available ligands with good stabilityas well as mild reaction conditions made these novel catalytic protocols quitevaluable.