4,5-b']difuran-4,8-dione synthesis

Yield: 42.1%

Reaction Conditions:

with n-butyllithium in tetrahydrofuran;hexane at 20; for 5.5 h;Cooling with ice;

Steps:

1-4
Place N,N-diethyl-furan-3-carboxamide (10g, 59.8mmol), 50mL of anhydrous THF in a 100mL single-necked flask,Under ice water bath, 37.5mL of n-LiBu hexane solution (1.6M, n-LiBu 60mmol) was added dropwise. After the addition was completed, the temperature was slowly raised to room temperature and stirred for 5.5 h.The mixture was poured into deionized water and stirred at room temperature for 6.0 h. Ion water and THF were spun out at 60°C by a rotary evaporator, and the crude product was transferred into quartz sand (100 mesh, 2 mm thick)/crude product/quartz sand (100 mesh, 3 mm thick)/silica gel (reagent grade, 300 mesh, 30 mm thick) )/Filter paper (single layer-qualitative filter paper, medium speed 102 type, Φ80mm)In the sand core funnel (Φ80.5mm) of the composite separation layer, wash with dichloromethane, 50mL each time, rinse 8-10 times, the color of the filtrate becomes transparent,The filtrate was spun out of methylene chloride by rotary evaporator at 30°C to obtain crude product. The crude product was vacuum dried at 50°C for 12h to obtain 2.37g of bright yellow benzodifuranone, as shown in Figure 2b.The yield was 42.1%, and the purity was 97%. The 1H-NMR chart is shown in FIG. 3b. As can be seen from FIG. 3b, the bright yellow benzofuranone has a high purity.

References:

Henan University;Gao Yueyue;Liu Rong;Wu Tianli;Dong Chen;Tan Furui;Yue Gentian;Zhang Weifeng CN110981884, 2020, A Location in patent:Paragraph 0016-0019