Referring to Scheme 8, in certain embodiments the thio carboxyl group of compounds of Formula R may be activated as acyl halides, acyl azides, symmetrical or unsymmetrical carboxylic, carbonic, or boronic anhydrides, acyl imidazoles, activated esters, phosphonium salts, uronium salts, or ammonium salts followed by ammonolysis of the activated intermediate either after prior isolation or in situ with an appropriately functionalized amine such as HN CH CH R to provide nitrogen mustard amides of Formula S priligy over the counter usa