反应详情

A solution of 1,8-dioxa-2-aza-spiro[4.5]dec-2-ene-3-carboxylic acid ethyl ester (3.00 g, 1.41 mmol, as prepared in the previous step) in MeOH (60 mL) and water (20 mL) was treated with LiOH (649 mg, 1.55 mmol) at rt for 2.5 h. MeOH was removed in vacuo. The resulting aqueous solution was acidified with 1 N aq HCl and extracted three times with EtOAc (100 mL, 100 mL, 50 mL). The combined organic extracts were dried over MgSO4 and concentrated in vacuo to afford the title compound (2.50 g, 96%) as a white solid. 1H-NMR (400 MHz, CDCl3) δ: 3.86-3.95 (m, 2H), 3.74 (dt, J=11.8, 4.7 Hz, 2H), 3.01 (s, 2H), 1.91-1.99 (m, 2H), 1.80-1.89 (m, 2H).

1. customMeOH was removed in vacuo
2. extractionextracted three times with EtOAc (100 mL, 100 mL, 50 mL)
3. dry with materialThe combined organic extracts were dried over MgSO4
4. concentrationconcentrated in vacuo