[I-].C[S+](C)C.[Li][CH2:7]CCC.[Cl:11][C:12]1[CH:21]=[C:20]2[C:15]([CH:16]=[CH:17][C:18](/[CH:22]=[CH:23]/[C:24]3[CH:25]=[C:26]([O:30][CH3:31])[CH:27]=[CH:28][CH:29]=3)=[N:19]2)=[CH:14][CH:13]=1>C1COCC1>[Cl:11][C:12]1[CH:21]=[C:20]2[C:15]([CH:16]=[CH:17][C:18]([CH:22]3[CH2:7][CH:23]3[C:24]3[CH:25]=[C:26]([O:30][CH3:31])[CH:27]=[CH:28][CH:29]=3)=[N:19]2)=[CH:14][CH:13]=1To trimethylsulfonium iodide (9.98 g, 2. eg.) in 60 mL of THF was added, at -10° C., 15 mL of n-BuLi (1.6M in hexane). The temperature was raised to room temperature for 2 hours. Then, at -10° C., the alkene (from Step 1) (7.037 g, 23.8 mmoles) in 30 mL of THF was added. After 30 minutes at -10° C., the reaction mixture was stirred overnight at room temperature. Hydrolysis with 25% aqueous NH4OAc, extractions with ethyl acetate and flash chromatography with toluene yielded the desired product.
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