The reaction of 5-(dimethylamino)naphthalene-1-sulfonyl chloride (I) with 4-nitroaniline (II) in pyridine gives the corresponding sulfonamide (III), which is reduced at the nitro group with hydrogen over Pd/C in ethanol, yielding the expected amine (IV). Finally, this compound is condensed with 3-hydroxy-2,2-dimethylpropionic acid (V) by means of propylphosphonic anhydride (PRPA) and triethylamine in dichloromethane/ethyl acetate.