Preparation | (1)2,2 '-[1-(tert-butoxy) pyrrolidine -3, 4-diyl] diacetic acid preparation. Dissolve potassium permanganate (1.49g,9.39mmol) in water (15mL), cool to 5 ℃, slowly add 3a,4,7,7a-tetrahydro-1 H-isoindole -2(3H)-tert-butyl formate (700mg,3.13mmol) in acetone (5mL) for 3 hours after adding. Add sodium bisulfite saturated solution to destroy excessive potassium permanganate, adjust the pH to 2 with 1N HCl, extract with dichloromethane (30mL × 3), wash with saturated salt water (30mL × 3), spin dry to obtain white foam solid 900mg, which is 2,2 '-[1-(tert-butoxy) pyrrolidine -3, 4-diyl] diacetic acid, without purification, proceed directly to the next reaction. (2) Preparation of 5-oxohexahydrocyclopentane [c] pyrrole-2 (1H)-tert-butyl formate. Dissolve 2,2 '-[1-(tert-butoxy) pyrrolidine -3, 4-diyl] diacetic acid (900mg,3.13mmol) in acetic anhydride (15mL), add sodium acetate (231mg,2.82mmol), and react at 120 ℃ for 2 hours. When the reaction liquid is cooled to room temperature, filtered, spin-dried, column chromatography purification (petroleum ether: ethyl acetate = 5:1) to obtain 390mg light yellow oil, which is 5-oxohexahydrocyclopentane [c] pyrrole -2(1H)-tert-butyl formate, two-step yield: 55%. |