Compound 3 (2.6g, 0.011mol)And 2-fluoro-5-formylbenzoic acid (2.1g, 0.012mol)Dissolved in anhydrous tetrahydrofuran (25ml), cooled to 0 ,Slowly add triethylamine (1.0ml, 0.007mol) dropwise, then warm up to room temperature for 5h, then slowly raise the temperature to 70 , add hydrazine hydrate (5.1ml, 0.107mol) for 3h, and drop to room temperature , Add appropriate amount of hydrochloric acid (2mol / L) to adjust the pH to acidic, no longer precipitate solids. Filter with suction, wash the product with water and ethyl acetate, and dry to obtain a yellow solid (1.9g, yield 83%)
