Methyl 1-aminocyclopropylcarboxylate (3.41g, 29.6mmol, 1.0eq) was dissolved in 40ml of sulfuric acid aqueous solution A (prepared by adding 1.62mL of 98% concentrated sulfuric acid to water, the molar equivalent of sulfuric acid was 1.0eq), ice The bath was cooled to 0-5° C., 10 ml of sodium nitrite (2.25 g, 32.6 mmol, 1.1 eq) aqueous solution was added to the reaction solution, and the mixture was stirred at room temperature for 1 hour. Then, the above reaction was added dropwise to 100 ml of refluxing sulfuric acid aqueous solution B (prepared by adding 1.62 mL of 98% concentrated sulfuric acid to water, and the molar equivalent of sulfuric acid was 1.0 eq). After the dropwise addition was completed, the heating was stopped, cooled to room temperature, and the reaction was detected by TLC, extracted three times with ethyl acetate (3*100 mL), the organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the organic phase was concentrated to obtain 1-hydroxyl -Methyl 1-cyclopropanecarboxylate (2.57 g, 22.1 mmol), colorless oily liquid, yield 74.8%.
