It will be apparent to the person skilled in the art that other diamine intermediates of general formula IV in Schemes 2 and 3 above, wherein R8 is other than methyl, may be prepared by replacing methyl iodide (CH3I) in step 4 above with the appropriate R8???X, wherein X is a leaving group such as Cl, Br, I, methanesulfonate (mesylate), p-toluenesulfonate (tosylate), trifluoromethanesulfonate (tri