A. Ethyl 3-(1-azetidinyl)propionate. A solution of 150 g. (2.00 moles) of 3-amino-1-propanol in 500 g. (5.00 moles) of ethyl acrylate (Note 1) is refluxed for 2 hours in a 1-l., round-bottomed flask. Subsequent vacuum removal of the excess ethyl acrylate at steam temperature yields 548 g.. (99%) of crude diethyl 3-N-(3-hydroxypropyl)iminodipropionate. A stirred, cooled solution of this material (548 g.) in 1 l. of chloroform and 10 ml. of N,N-dimethylformamide is treated dropwise with 262 g. 2.20 moles) of thionyl chloride. By cooling with an ice bath and controlling the addition rate, the reaction temperature is maintained below 40° (Note 2). After the addition is complete, the reaction mixture is stirred for 30 minutes at room temperature and poured slowly into a slurry of 340 g. of sodium hydrogen carbonate in 1 l. of water (Note 3). The organic layer is separated (Note 4) and dried over sodium sulfate, and the solvent is removed under reduced pressure, below 50°, yielding 570 g. (97%) of crude diethyl 3-N-(3-chloropropyl)iminodipropionate. A mixture of 100 g. of this crude material, 200 g. of anhydrous, powdered sodium carbonate (Note 5), and 10.0 g. of pentaerythritol (Note 6) in 200 ml. of diethyl phthalate is placed in a 500-ml., round-bottomed flask fitted with a vacuum-distillation head and an effective stirrer. The system is evacuated through a trap of sufficient capacity to contain 50 ml. of liquid, and the product is distilled by heating the stirred suspension with a heating mantle at 10–15 mm. By proper adjustment of the heat source, the distillation temperature is maintained below 150°, minimizing codistillation of diethyl phthalate. The distillate is collected until the head temperature cannot be kept below 150°. Redistillation of the resulting crude product through a 4-in. Vigreux column yields 34.0 g. (57–68%) of ethyl 3-(1-azetidinyl)propionate, b.p. 86–87° (12 mm.), 99% pure by GC (Note 7).

B. Azetidine. A stirred mixture of 38 g. (0.68 mole) of potassium hydroxide pellets in 100 ml. of white mineral oil (Note 8) is heated to 140–150° in a four-necked, 500-ml., round-bottomed flask, fitted with an air-driven Hershberg stirrer, a thermometer, a dropping funnel, and a 6-in. Vigreux column fitted with a vacuum-distillation head. The flask is removed from the heat source, and 50 g. (0.32 mole) of purified ethyl 3-(1-azetidinyl)propionate is added dropwise at a rate sufficient to maintain the reaction temperature at 150° (Note 9). After addition is complete, the reaction mixture is heated to 200° at 50 mm. to remove all traces of ethanol (Note 10). The flask is fitted with a distillation head and a nitrogen bubbler, and the distillation is resumed at atmospheric pressure until azetidine distills (210° maximum pot temperature, (Note 11)). The resulting product (19.6 g., 85% purity) is dried over potassium hydroxide and redistilled through a short Vigreux column yielding 14.5–15.8 g. (80–87%) of purified azetidine, b.p. 62–63° (Note 12).