Synthesis
The general procedure for the synthesis of tetrahydro-5-oxo-2-furancarboxylic acid from 2-aminoglutaric acid is as follows:
(1) 140 mL of concentrated hydrochloric acid was slowly added to a solution containing compound 1 (2-aminoglutaric acid, 270 mL of water as solvent) at room temperature and protected by nitrogen, and exothermic phenomena were observed. After the system became clear, it was cooled to 0°C. 70.3 g of sodium nitrite (dissolved in 200 mL of water) was slowly added to the system at 0°C, taking care to control the temperature. The system gradually turned green and turbid, and the dosing process continued for 15 minutes, keeping the temperature at about 2°C. The system was cooled to 0°C. After completion of the dropwise addition, the reaction was continued at 0°C. Subsequently, the reaction solution was concentrated directly to dryness at 50°C using an oil pump. The concentrated dry mass was pulped with 400 mL of ethyl acetate and filtered. The filter cake was again pulped once with 400 mL of ethyl acetate and then the cake was washed with 200 mL of ethyl acetate. All filtrates were combined and dried by pump at 45°C to give a final 104 g of yellow oily liquid (Compound 2).
References
[1] Chemische Berichte, 1961, vol. 94, p. 2106 - 2114
[2] Chemistry and Industry (London, United Kingdom), 1959, p. 1413
[3] Justus Liebigs Annalen der Chemie, 1890, vol. 260, p. 128
[4] Patent: CN106748972, 2017, A. Location in patent: Paragraph 0022; 0023; 0024; 0030
