Gold(I) Complexes of Conformationally Constricted Chiral Ferrocenyl Phosphines

The preparation of two new chiral, enantiopure, and conformationally
constrained phosphocin and 1,5-diphosphocin, incorporating two ferrocenyl
units, is described. The gold­(I) chloride complexes of these ligands
and (S)-(R)-PPF-OMe were prepared,
and their structures, in solution and solid states, are compared.
Abstraction of the chloride anion by the addition of silver salt of
either toluenesulfonate or chiral BINOL-phosphates generates active
catalysts for the intramolecular cyclization of 6-methyl-1,1-diphenylhepta-4,5-dien-1-ol,
where up to 47% ee can be obtained. Match and mismatch effects between
chiral ligands and counteranions are highlighted.