Abstract: D-tetramisole, or its l-tetramisole enantiomer, is racemized in solution in dimethylsulphoxide in the presence of a catalytically effective amount of potassium hydroxide.

Abstract: Compounds of the formula: ##STR1## and pharmaceutically acceptable acid addition salts thereof wherein R, R.sub.1, R.sub.2, R.sub.3, are selected from the group consisting of hydrogen, halogen and lower-alkyl of from one to four carbon atoms, inclusive; with the proviso that taken together they constitute the following substituents on the tetracydic ring, 10-halo, 8,10-dihalo, 8,9-di-lower-alkyl, and 7,9-dilower-alkyl; R', R'.sub.1, R'.sub.2, and R'.sub.3 are selected from the group consisting of hydrogen, halogen and lower alkyl of from one to four carbon atoms, inclusive, with the proviso that when taken together they constitute the following substituents, 1-halo, 2-halo, 3-halo, 4-halo, 1-lower-alkyl, 2-lower-alkyl, 3-lower-alkyl, 4-lower-alkyl, 1,3-dihalo, 2,3-dihalo, 2,4-dihalo, 3,4-dihalo, 1,3-di-lower-alkyl, 2,3-di-lower-alkyl, 1,4-di-lower-alkyl; R.sub.4, R.sub.5, R.sub.6, and R.sub.

Abstract: A method for the attainment of enhanced enantioselectivity in the reduction of 3-acyl derivatives of 1-(2-alkoxyethyl)-4-phenyl-imidazolin-2-ones to the optically active 3-acyl derivatives of 1-(2-alkoxyethyl)-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 bis-tertiary phosphines to achieve maximum enantioselectivity. The methods for preparing the iodide salts are disclosed.