Abstract: A method for making a chiral transition metal-ligand catalyst complex that is active in catalyzing stereoselective ring opening reactions includes contacting an asymmetric tetradentate ligand, in an excess of a Brønsted acid, with a salt of a first row transition metal, wherein the acidity of the conjugate acid of the salt is the same as or less than the acidity of the Brønsted acid, under conditions effective to allow formation of the active chiral transition metal-ligand catalyst complex, and forming a solution of the complex in a water-miscible, protic solvent from which the active complex can be precipitated by the addition of water and adding water to the solution to precipitate at least a portion of the complex.

Abstract: A method for making a chiral transition metal-ligand catalyst complex that is active in catalyzing stereoselective ring opening reactions includes contacting an asymmetric tetradentate ligand, in an excess of a Brønsted acid, with a salt of a first row transition metal, wherein the acidity of the conjugate acid of the salt is the same as or less than the acidity of the Brønsted acid, under conditions effective to allow formation of the active chiral transition metal-ligand catalyst complex, and forming a solution of the complex in a water-miscible, protic solvent from which the active complex can be precipitated by the addition of water and adding water to the solution to precipitate at least a portion of the complex.