Bile Acid Derived Tropos Vaulted Bi­naphth­ylphosphites: Synthesis, Stereo­chemical Characterization and Complexation to Rhodium

Abstract

AbstractThree different 2,2′‐binaphthylphosphites were synthesized, starting from suitable derivatives of cholic or deoxycholic acids and 1,1′‐dihydroxy‐2,2′‐binaphthyl, and their stereochemical features were analyzed by CD and NMR spectroscopy. The spectroscopic data clearly demonstrate the capability of the cholestanic backbone to induce a M prevalent screw sense to the flexible binaphthyl moiety, giving rise to tropos ligands. The extent of the prevalence of the M sense of twist depends on the position at which the binaphthylphosphite moiety is linked on the bile acid skeleton. The three phosphites were mixed with [Rh(COD)2][BF4] and the resulting complexes were analyzed by variable temperature 31P NMR spectroscopy, thereby obtaining information on their stereochemical characteristics, which reflect the different asymmetric induction capability of the ligands.