Benzenesulfonyl chloride → t-butyl 4-(1-benzenesulfonyl-1H-indol-4-yl)piperazine-1-carboxylate

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Reaction Steps

A mixture of 165 mg (0.55 mmole) 4-(1H-indol-4-yl)-piperazine-1-carboxylic acid tert-butyl ester, 25 mg tetrabutylammonium hydrogen sulfate and 0.08 mL (0.6 mmole) benzenesulfonyl chloride in 2 mL 4 M sodium hydroxide and 5 mL toluene was stirred at room temperature for 2 hours. The mixture was diluted with 5 mL water and extracted with 25 mL ethyl acetate. The organic phase was washed with 5 mL water, 5 mL saturated sodium chloride, dried (magnesium sulfate) and concentrated. 4-(1-Benzenesulfonyl-1H-indol-4-yl)-piperazine-1-carboxylic acid tert-butyl ester was isolated by recrystallization from ether/hexane, 223 mg, m.p. 143-144° C.

Provenance & Evidence