Iodide salts of certain rhodium complexes of asymmetric diphosphines, their preparation and their use in enhancement of enantioselectivity in the products of their reduction of prochiral imidazolinones

Abstract From the Canadian patent

A method for the attainment of enhanced enantioselectivity in the reduction of 3-acyl derivatives of 1-(2-alkoxyethyl)-4-phenylimidazolin-2-ones to the optically active 3-acyl derivatives of 1-(2alkoxyethyl)-4-phenyl-2-imidazolidones for use in the direct manufacture of levamisole, (-), 2, 3, 5, 6-tetrahydro-6-phenylimidazo-2,1-b-thiazole useful as an anthelmintic has been discovered. The method involves the preferred use of iodide salts of Rh(I) complexes of optically active bistertiary phosphines of the formula:, to achieve maximum enantioselectivity. The methods for preparing the iodide salts are disclosed.