Yield:885270-86-0 80%

Reaction Conditions:

with sodium hydrogencarbonate in water at 20; for 1.5 h;

Steps:

2.1 Step 1) 2,7-diazaspiro[3.4]octane-7-carboxylic acid tert-butyl ester

Sodium bicarbonate (10.0 g, 119 mmol)Add to a solution of 2,7-diazaspiro[3.4]octane-7-carboxylic acid tert-butyl ester oxalate (3.0 g, 9.9 mmol) in water (10 mL)The reaction was carried out at room temperature for 1.5 hours. Extracted with dichloromethane/methanol (v/v = 9/1, 80 mL x 3),The combined organic phases were washed with a saturated sodium chloride solution (50 mL×2). Dry over anhydrous sodium sulfate and concentrate by suction filtration.The title compound was obtained (1.68 g, yield 80%). It is a yellow oil.

References:

CN109928971,2019,A Location in patent:Paragraph 0213; 0215; 0216; 0217