title: Modular ligand variation in calcium bisimidazoline complexes: effects on ligand redistribution and hydroamination catalysis.
abstract: A series of calcium complexes supported by chiral bisimidazoline ligands have been studied in the catalytic intramolecular hydroamination/cyclisation of amino-olefins. The complexes [Ca(R-BIM){N(SiMe(3))(2)}(THF)] (R = 4-C(6)H(4)Me, 5a, 4-C(6)H(4)F, 5b and (t)Bu, 5c) have given competitive enantioselectivities (up to 12%) when compared to current literature studies involving calcium. Bisimidazolines offer a significant advance over similar bisoxazoline ligands, by allowing a greater structural variance through a modular synthetic pathway.
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, UK CF10 3AT.
authors.forename: James S
authors.initials: JS
authors.lastname: Wixey
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Ward