[Mg].II.Br[CH:5]([CH2:7][CH2:8][CH3:9])[CH3:6].[CH2:10]([N:17]1[CH2:21][CH:20]([CH2:22]I)[CH2:19][C:18]1=[O:24])[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1>C1COCC1>[CH2:10]([N:17]1[CH2:21][CH:20]([CH2:22][CH:5]([CH3:6])[CH2:7][CH2:8][CH3:9])[CH2:19][C:18]1=[O:24])[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1
To a suspension of magnesium turnings (0.50 g, 0.021 mol) in 15 mL of dry THF under nitrogen, was added an iodine crystal and 2-bromopentane (2.88 g, 0.019 mol). After an exothermic reaction which was periodically cooled in an ice bath, the reaction was stirred at room temperature for 2 hours. Eight milliliters of Li2CuCl4 (made from 84 mg LiCl and 134 mg CuCl2 in 10 mL of dry THF) was added at 0° C. followed by dropwise addition of 1-Benzyl-4-iodomethyl-pyrolidine-2-one 75 in 15 mL dry THF, and the resulting suspension was let stir at 0° C. for 3 hours. Stirring was continued at room temperature for 1 hour before quenching with a saturated solution of ammonium chloride. Water was added to dissolve the precipitate formed, and the solution was then extracted with ether and dried over magnesium sulfate. The solvent was evaporated under vacuum and the residue chromatographed on silica eluting with 1:1 acetone/hexane to give 1.13 g, 69% of the 1-benzyl-4-(2-methyl-pentyl)-pyrrolidin-2-one 76. 1H NMR (CDCl3) δ 7.30 (m, 5H), 4.44 (m, 2H), 3.32 (m, 1H), 2.86 (m, 1H), 2.56 (m, 1H), 2.40 (m, 1H), 2.10 (m, 1H), 1.30 (m, 6H), 1.10 (m, 1H), 0.90 (m, 6H). MS, m/z (relative intensity): 261 [M+2H, 100%], 301 [M−H+CH3CN, 82%], 260 [M+H, 72%].
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