Catalytic Pd-Mediated Approach to Enantiopure Phosphorus Ligands

Significance

With the goal of studying the influence of the nature of the P-substituent on the 2,5-diphenylphospholane ligand properties, efficient synthetic methods for a range of enantiopure substituted P-aryl-2,5-diphenylphospholane oxides D and boranes F have been developed. The phosphinoboranes F were prepared by three different approaches from readily available corresponding enantiopure diarylphosphine oxide A, borane B or phosphinoyl chloride C in high yields and without racemization. The known phosphinoyl chloride method has some advantage over the catalytic C-P cross-coupling approaches in terms of yield but presents narrow scope. Rh-catalyzed reduction of 2,5,P-triphenylphospholane oxide affords the corresponding bulky and electron-rich tricyclohexyl derivative in excellent yield.