[OH-].[Na+].[NH2:3][CH2:4][CH:5]1[CH2:7][CH2:6]1.[Br:8][CH:9]([CH2:13][CH2:14]Cl)[C:10](Cl)=[O:11].O>S([O-])(O)(=O)=O.C([N+](CCCC)(CCCC)CCCC)CCC.ClCCl>[CH:5]1([CH2:4][N:3]2[CH2:14][CH2:13][CH:9]([Br:8])[C:10]2=[O:11])[CH2:7][CH2:6]1
In a 1.5-liter 4-necked flask, equipped with a stirrer, dropping funnel, reflux condenser, thermometer and argon inlet, 54.4 g sodium hydroxide pearls (1.36 mol) and 9.26 g tetrabutylammonium hydrogensulfate (27.3 mmol) were suspended with stirring at room temperature under argon in 500 ml dichloromethane. To the suspension 35.6 g aminomethylcyclopropane (500 mmol) were added. A solution of 100.0 g 2-bromo-4-chlorobutyric acid chloride (400 mmol, product of Example 1) in 100 ml dichloromethane was added during 10 min. After the first 3 min. of addition, reflux was reached and maintained during the addition. After completed addition, the mixture was refluxed for 1 h, during which its color changed from dark green to dark brown. The suspension was cooled to room temperature during 10 min., and a mixture of 50 g ice and 250 ml deionized water was added under stirring. The phases were separated and the organic layer was successively washed with a solution of 60 g ammonium chloride in 300 ml deionized water, followed by 300 ml deionized water. The organic layer was concentrated to yield 94.2 g of N-cyclopropylmethyl-3-bromopyrrolidine-2-one as a dark oil.
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