SyntheticPage 297
Published Aug 28, 2008
D-aspartic acid (6.083 g, 0.045 mol), Ca(OH)2 (1.653 g, 0.023 mol), NaOH (50% aqueous w/v, 3.60 g), and deionized water (8.5 ml) were placed in a 3-necked round bottom flask, and fitted with a water condenser. 1,2-dibromoethane (1.6 ml, 3.47 g, 0.018 mol) was added through one of the side arms. The reaction mixture was heated to reflux. Over approximately 6 h NaOH (50% aqueous w/v, 2.98 g) was added dropwise using a syringe pump, whilst under reflux. Water (20 ml) was added, and the system refluxed for a further hour. The system was cooled to room temperature, then acidified to pH 3 using HCl (35%). A white precipitate was collected and was placed in water (23 ml). NaOH (50% aqueous w/v) was added until pH 11, then HCl (35%) was added carefully until pH 3.5. The white precipitate was collected, and dried under vacuum at 65 °C. Yield: 1.417 g, 26%