Optically Active Transition-Metal Complexes. 10.¹ Bifunctional Arene−Chromium−Tricarbonyl Complexes Derived from (<i>R</i>)-Phenylethanamine: Easily Accessible Planar-Chiral Diphosphines and Their Application in Enantioselective Hydrogenation, Hydroamination, and Allylic Sulfonation

Abstract

(R)-[{α-(Dimethylamino)ethyl}-η6-benzene]Cr(CO)3 is stereoselectively substituted in the ortho-position with PPh2, P(O)Ph2, and CO2R groups. After exchange of the amino group for a chloro substituent with chloroformic esters, a variety of phosphorus, nitrogen, and oxygen nucleophiles can be diastereoselectively introduced into the α-position to generate bifunctional chelating ligands. The addition of cyanide is not fully diastereospecific. The diphosphines, structurally similar to the well-known "Josiphos"-ferrocenes, are good catalysts for rhodium-catalyzed enantioselective hydrogenation, iridium-catalyzed hydroamination, and palladium-catalyzed allylic sulfonation.