Phosphoramidite-Transition Metal Catalyzed Cross-Coupling Reactions

The cross-coupling reaction has recently become one of research focuses in organic synthetic chemistry. The design and synthesis of phosphoramidite ligands and their application in palladium-catalyzed Suzuki reactions and copper-catalyz- ed N-arylation reactions respectively were developed in this paper.Derived from simple, readily available phosphorus trichloride, secondary amines and phenols, six types and forty-two phosphoramidite ligands were designed and synthesized by simple two steps.Using Pd(OAc)₂ as catalyst precursor, the condition of Suzuki cross-coupling reaction between aryl bromides and aryl boronic acids has been optimized. Pd(OAc)₂/5c/K₃PO₄/dioxane was selected as the best catalytic system. High yields of the relative products under the optimized reaction conditions were obtained and TON could be up to 104.When CuBr was used as catalyst precursor, relatively better reaction condition CuBr/2d/Cs₂CO₃/DMF had been screened out. The cross-coupling reactions between aryl iodides and primary alkylamines could be carried out successfully and generally afforded the products with high yields; Secondary amines could also be coupled with aryl iodides, however, the yields were slightly lower than primary amines. Besides alkylamines, N-H heterocycles were also suitable substrates, and some bromoheterocycles gave good results.