Synthesis, stereochemical characterisation and use as chiral ligands in the copper catalyzed conjugate addition of diethylzinc to acyclic enones of tropos deoxycholic acid-derived biphenylphosphites

Three new deoxycholic acid-based 5,5’ substituted biphenylphosphites, 2-4, were synthesized and their stereochemical features were assayed by CD and NMR spectroscopies, which allowed us to determine the sense of twist of the substituted biphenyl moiety as well as the extent of its prevalence in different solvents. Phosphites 1-4 were used as chiral ligand in the copper catalyzed conjugate addition of diethylzinc to acyclic enones, affording the alkylation products with e.e.s up to 65%. The results obtained allowed a correlation between asymmetric induction and sense of twist of the biphenylphosphite moiety of the chiral inducers to be made.