3339-73-9 3-Phthalimidopropionic acid

1.1; 2.1 1. Synthesis of phthalic anhydride alanine: Add 100g (1.12mol) of alanine to a 1000mL three-necked flask,170g (1.15mol) of phthalic anhydride, 5g of triethylamine and 650mL of toluene were heated to reflux reaction, water was separated during the reaction, the reaction was carried out until no water drops, the temperature was lowered to 20 ° C, the temperature was kept for 2 hours, suction filtration, filter cake baking Dry 240.2 g of phthalic anhydride alanine, HPLC purity 99.1%, yield 97.7%.
I-16.1 Synthesis of 3-(l,3-dioxo-2,3-dihydro-lH-isoindol-2-yl)propanoic acid Into a 3-L 4-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed a solution of 3-aminopropanoic acid (20 g, 224.48 mmol, 1.00 equiv) and 1,3- dihydro-2-benzofuran-l,3-dione (33.28 g, 224.69 mmol, 1.00 equiv) in acetic acid (1,200 mL). This was followed by the addition of potassium acetate (66.0 g, 672.49 mmol, 3.00 equiv) in several batches at 0 °C. The resulting solution was stirred for 3 h at 80 °C in an oil bath. The resulting mixture was concentrated under vacuum. The reaction was then quenched by the addition of 150 mL of water. The solids were collected by filtration. This resulted in 40 g (81%) of 3-(l ,3-dioxo-2,3- dihydro-lH-isoindol-2-yl)propanoic acid as a white solid. R/. 0.15 (in ethyl acetate:petroleum ether = 1 : 1)
A mixture of β-alanine (5.0 g, 0.056 mol), phthalic anhydride (8.7 g, 0.059 mol),and DMF (20 mL) was refluxed under stirring for 3 h. The resulting mixture was cooled to room temperature, poured into ice-water (~100 mL), and then filtered by suction. The filter cake was sequentially washed with water (15 mL × 3), alcohol (3 mL × 3), and ether (10 mL × 2), and then dried in vacuo to give 2e (9.9 g, 80%) as a white solid.
137.6 Step 6: A mixture of isobenzofuran-l,3-dione (20 g, 135 mmol) and 3-aminopropanoic acid (12 g, 135 mmol) was stirred at 170°C for 6h. See Figure 2. Upon reaction completion, the mixture was diluted with water and extracted with DCM (100 mL x 3). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give 3-(l,3-dioxoisoindolin-2-yl)propanoic acid 137g (20 g, 69%) as a white solid.
3-Phthalimidopropanoic acid (4) A mixture of phthalic anhydride (0.32 g, 2.2 mmol) and b-alanine (0.19 g, 2.2 mmol) was heated in an open flask to 150˚C for 2 h. After cooling to rt, H2O (5 mL) was added and the reaction mixture was extracted in CH2Cl2 (2 X 20 mL). The organic layer was dried over Na2SO4, filtered and concentrated to give a white solid (0.3 g) in 62% yield; IR (KBr) 1711, 2954 cm-1; mp 140-141˚C. The product was used in the next step without further purification.