[CH:1]1([C:4]([N:6]2[CH2:10][CH2:9][C@@H:8]([CH2:11][C:12]([O:14]CC)=O)[CH2:7]2)=[O:5])[CH2:3][CH2:2]1.O.[NH2:18][NH2:19]>C(O)C.ClCCl>[CH:1]1([C:4]([N:6]2[CH2:10][CH2:9][C@@H:8]([CH2:11][C:12]([NH:18][NH2:19])=[O:14])[CH2:7]2)=[O:5])[CH2:3][CH2:2]1In a round bottom flask equipped with reflux condenser, an orange solution of ethyl [(3S)-1-(cyclopropylcarbonyl)-3-pyrrolidinyl]acetate (56.1 g, 249 mmol) in ethanol (356 mL) was treated with hydrazine monohydrate (242 mL, 4.98 mol). The resultant yellow solution was stirred at 80° C. (reflux) for 15 h. The reaction was cooled to room temperature and concentrated in vacuo. Ethanol (100 mL) was added and the reaction was concentrated (2×) to give a pale yellow clear oil. The oil was dissolved in dichloromethane (white solution observed), dried over MgSO4, concentrated in vacuo, and pumped under high vacuum overnight (16 h) to give the title compound as a clear pale yellow oil (249 mmol, quantitative). MS(ES)+ m/e 212.0 [M+H]+, 423.2 [2M+H]+.
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