A stirred, 0° C. solution of ethyl 4-[5-[3-ethoxycarbonylmethoxy-4-[N,N-bis(1-methylethyl)aminocarbonyl]phenoxy]pentyloxy]benzenecarboximidoate monohydrochloride (400 mg, 0.68 mmol) in 25 mL of anhydrous ethanol is treated with 1.36 mL of 1.0N aqueous sodium hydroxide. After stirring 1.5 hours, the reaction is concentrated in vacuo. The resulting 5-[5-[4-(ethoxyiminomethyl)phenoxy]pentyloxy]-2-[N,N-bis(1-methylethyl)carbamoyl]phenoxyacetic acid is then dissolved in 50 mL of anhydrous ethanol in a pressure tube, and treated with ammonium chloride (500 mg, 9.4 mmol). This mixture is treated with anhydrous ammonia for 2 minutes at 0° C. The pressure tube is sealed and heated to 50° C. for 1 hour. Upon cooling and concentrating in vacuo, the resulting material is purified by chromatography on silica gel (15 g) with 20-30% methanol/dichloromethane as the eluent to afford a colorless foam. The resulting 5-[5-[4-(aminoiminomethyl)phenoxy]pentyloxy]-2-[N,N-bis(1-methylethyl)carbamoyl]phenoxyacetic acid monohydrochloride is then dissolved in 150 mL of anhydrous ethanol at 0° C. and treated with anhydrous hydrogen chloride gas over 30 minutes. This solution is stirred at room temperature for 20 hours and the resulting solution is concentrated in vacuo. The resulting material is purified by chromatography on silica gel (15 g) with 5-20% methanol/dichloromethane as the eluent to afford ethyl 5-[5-[4-(aminoiminomethyl)phenoxy]pentyloxy]-2-[N,N-bis(1-methylethyl)carbamoyl]phenoxyacetate monohydrochloride as colorless foam; CHN calculated for
