[H-].[Na+].[Br:3][C:4]1[C:8]([Cl:9])=[C:7]([CH3:10])[NH:6][C:5]=1[C:11]([O:13][CH2:14][CH3:15])=[O:12].[CH3:16][Si:17]([CH:20](Cl)[CH2:21]C)([CH3:19])[CH3:18].CN([CH:27]=[O:28])C>>[Br:3][C:4]1[C:8]([Cl:9])=[C:7]([CH3:10])[N:6]([CH2:27][O:28][CH2:21][CH2:20][Si:17]([CH3:19])([CH3:18])[CH3:16])[C:5]=1[C:11]([O:13][CH2:14][CH3:15])=[O:12]To a suspension of sodium hydride (76 mg, 3.16 mmol) in dry DMF (5 ml), solution of ethyl 3-bromo-4-chloro-5-methyl-1H-pyrrole-2-carboxylate (Intermediate 267, 420 mg, 1.58 mg) was added, the resulting mixture was stirred at 0° C. for 30 minutes until gas evolution seized. Trimethylsilyl-ethylmethyl chloride (315 mg, 1.89 mmol) was added drop wise and stirred over night while allowing the reaction mixture warmed up to room temperature slowly. The reaction was quenched with cold water, diluted with ether (20 ml), washed with water and brine, the organic layer was dried over anhydrous sodium sulfate, concentrated and purified by column chromatography (95% hexanes in ethyl acetate) to give the desired product as an oil (624 mg).
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