To a solution of 1.49 g (4.59 mmol) of N-(4-bromophenyl)-N-methyl benzenesulfonamide (see Preparative Example A, Step C) in 37.5 mL THF at −78° C. was added dropwise 5.94 mL (10.10 mmol) of a 1.7 M solution of tert-BuLi in pentane and the resultant mixture was stirred at −78° C. for 15 min. To this mixture was then added a solution of 1.01 g (6.59 mmol) of N-methoxyethylpyrrole-2-carboxaldehyde in 6 mL THF and the mixture was allowed to gradually warm to −30° C. over a 4 h period. After this time, the reaction mixture was quenched by the addition of a saturated aqueous solution of ammonium chloride and extracted with EtOAc. The combined organic layers were dried over Na2SO4, filtered and the filtrate was concentrated. The residue was purified by chromatography on silica gel (hexanes:EtOAc, 13:7) to give the title compound.
