Asymmetric synthesis of cyano- functionalised-1, 3-diphosphine via organopalladium promoted hydrophosphination reaction.

Abstract

The asymmetric hydrophosphination reaction involving (Triphenylphosphoranylidene)acetonitrile and diphenylphosphine was carried out by utilizing palladium complex containing ortho-metalated (R)-(dimethylamino)ethyl)naphthalene as the chiral auxiliary. The cyano-functionalized monophosphine substrate were synthesized from 3- chloro-1,1-diethoxypropane via a versatile one-pot process. Subsequent hydrophosphination of coordinated cyano-functionalized phosphine substrates promoted by the chiral auxillary gave corresponding functionalized 1, 3-diphosphine product. Functional group transformation of the cyano group to formyl group was performed by selective reduction of diphosphine palladium complex by using DIBAL-H. The reaction proceeded regiospecifically and stereospecifically to give the corresponding formyl-functionalised 1, 3-diphosphine products. The coordination properties and absolute configurations of the novel formyl-functionalized 1, 3-diphosphine complexes were established by single crystal X-ray crystallography. The enantiomerically pure formyl functionalized diphosphine ligand could be subsequently liberated stereospecifically by treatment of the corresponding dichloro palladium complexes with aqueous potassium cyanide in high yield.