To a solution of 3.53 g of 4-(4-hydroxybutyl)-epsilon-caprolactone in 14 ml methylene chloride and 14 ml tetrahydrofuran is added 4.24 g p-chlorophenylsulfonamide followed by 7.44 g triphenylphosphine. The reaction mixture is stirred at room temperature for 0.5 h and then 6.1 ml diethyl azodicarboxylate is added slowly with cooling. After the addition, the cooling bath is removed and the solution is stirred at room temperature overnight. The reaction mixture is evaporated to dryness to yield 4-[4-(p-chlorophenylsulfonamido)butyl)-epsilon-caprolactone.
