The condensation of 3-ethyl-4-methyl-3-pyrrolin-2-one (I) with 2-phenylethyl isocyanate (II) at 150 C gives 3-ethyl-4-methyl-2-oxo-N-(2-phenylethyl)-3-pyrrolin-1-carboxamide (III), which is sulfonated with chlorosulfonic acid at 40 C to yield the corresponding benzenesulfonyl chloride (IV). The reaction of (IV) with concentrated NH4OH affords the sulfonamide (V), which is finally condensed with 4-methylcyclohexyl isocyanate (VI) in acetone.