Process for the stereoselective synthesis of 16-substituted-4-aza-androstanones

A process for producing a compound of structural formula (A):

• ##STR11## wherein:
• the dotted line "a" is a single bond or double bond;
• R.sup.1 is H or CH.sub.3 ;
• R.sup.2 is H or CH.sub.3 ;
• and
• Ar is an unsubstituted mono- or di-substituted phenyl, naphthyl, or 5 or 6 membered heteroaromatic ring containing at least one member selected from the group consisting of:
• one ring oxygen atom, one ring sulfur atom, 1-4 ring nitrogen atoms, or combinations thereof;
• in which the heteroaromatic ring can also be fused with one benzo or heteroaromatic ring;
• produced by:
• treating a compound of structural formula (B):
• ##STR12## with Ar--OH and cesium carbonate in a polar aprotic solvent selected from DMSO, DM F, nitromethane, dioxane, THF, and acetonitrile, and wherein Ar is as defined above.