[Li+].[CH3:2][CH:3]([N-]C(C)C)C.[CH3:9][C:10]1[N:11]([C@H:16]2[CH2:20][C@@H:19]([C:21]([O:23][CH3:24])=[O:22])[CH:18]=[CH:17]2)[C:12]([CH3:15])=[CH:13][CH:14]=1.C(I)C.[NH4+].[Cl-]>O1CCCC1>[CH3:15][C:12]1[N:11]([C@H:16]2[CH2:20][C@@:19]([CH2:2][CH3:3])([C:21]([O:23][CH3:24])=[O:22])[CH:18]=[CH:17]2)[C:10]([CH3:9])=[CH:14][CH:13]=1A −40° C. solution of 2M (in THF/ethylbenzene/heptane) LDA (68 ml, 138 mmol) in tetrahydrofuran (120 ml) was treated with methyl (1R,4S)-4-(2,5-dimethyl-1H-pyrrol-1-yl)cyclopent-2-ene-1-carboxylate (14.02 g, 63.9 mmol) while keeping the temperature less than −33° C. The cold reaction was stirred for 40 minutes and then a solution of ethyl iodide (13.63 g, 87.4 mmol) in tetrahydrofuran (5 ml) was added slowly while keeping the temperature less than −33° C. The reaction was stirred with the cold bath in place for four hours and allowed to slowly warm. The reaction was poured into NH4Cl soln (300 ml), then extracted with ethyl acetate (2×200 ml), washed with brine dried over MgSO4, and concentrated under reduced pressure. The resulting brown oil was passed through a column of silica gel with 10% ethyl acetate/hexanes to give methyl (1R,4S)-4-(2,5-dimethyl-1H-pyrrol-1-yl)-1-ethylcyclopent-2-ene-1-carboxylate as a brown oil (12.96 g, 82%).
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