Phcnylsulfonyl indole

NaBFI pellets (10-12 eq.) were added to TFA (25 ml) over 30 min. Hthyl 4-[I-(phcnylsulfonyl)indol-3-yl]-4-oxobutanoate (1.5 mmol) was then added as... 

Several methods for synthesizing N-protected (usually with electron-withdrawing groups) 2-and 3-haloindoles have been developed and the resulting haloindoles are much less prone to decomposition than the unsubstituted compounds. Bromination of N-(phcnylsulfonyl)indole (3), which is readily available via lithiation [9, 10] or phase-transfer chemistry [11, 12], affords 3-bromo-l-(phenylsulfonyl)indole (4) in nearly quantitative yield [12]. 

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