3-Oxabicyclo[3.1.0]hexane-2,4-dione

1489-58-3

5617-74-3

In a 500 mL three-necked flask, cyclopropane-1,2-dicarboxylic acid (130 g, 1 mol) was mixed with acetic anhydride (255 g, 2.5 mol) and heated in an oil bath to about 140 °C and kept at reflux while mechanically stirring. After 2 hours of reflux reaction, the mixture of acetic acid and acetic anhydride was slowly added and the temperature was gradually raised to 220°C. At this temperature, the reaction was continued for 1 hour. Upon completion of the reaction, the mixture was cooled to about 120 °C, followed by vacuum distillation (1 mmHg, 106-108 °C) to purify the product to afford 3-oxabicyclo[3.1.0]hexane-2,4-dione (87 g, GC purity: 99.82%, yield: 81%). The product was white crystal with the melting point of 56-58 °C (literature value: 54-56 °C).1H-NMR (300 MHz, DMSO-d6) data were as follows: δ 2.90-2.94 (2H, m), 1.81-1.85 (1H, m), 1.59-1.67 (1H, m).