[C:1]([O:5][C:6]([N:8]1[C:11]([CH3:13])([CH3:12])[CH2:10][C:9]1=[O:14])=[O:7])([CH3:4])([CH3:3])[CH3:2].[OH-:15].[Li+]>O1CCCC1.CCOCC.O>[C:1]([O:5][C:6]([NH:8][C:11]([CH3:13])([CH3:12])[CH2:10][C:9]([OH:14])=[O:15])=[O:7])([CH3:4])([CH3:3])[CH3:2]A 3 L, 3-neck round bottom flask equipped with a magnetic stirrer, thermometer, nitrogen bubbler and addition funnel was charged with 180.3 g (0.89 mol) of N-(t-butoxycarbonyl)-4,4-dimethylazetidin-2-one dissolved in 1 L of tetrahydrofuran. The solution was cooled to 0°-5° C. and treated dropwise with 890 mL of 1.0M aqueous lithium hydroxide over 30 minutes. The reaction mixture was stirred at 0°-5° C. for 2 hours then diluted with 1 L of ether and 1 L of water. The layers were allowed to separate and the aqueous layer reextracted with an additional 1 L of ether. The aqueous layer was acidified by the addition of 1 L of saturated aqueous sodium bisulfate, then extracted with 1×1 L and 2×500 mL of ether. The combined organic layer and ether extracts were washed with 500 mL of saturated aqueous sodium chloride, dried over magnesium sulfate and concentrated under vacuum to 173 g of a yellow oil that solidified upon standing. The material was slurried with warm hexane then filtered and dried under high vacuum to afford 168.5 g (0.775 mol, 87%) of product as a white solid. 1H NMR (200 MHz,CDCl3): 1.39 (s,6H), 1.44 (s,9H), 2.72 (s,2H). FAB-MS: calculated for C10H19NO4 217; found 218 (M+H,54%).
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