To a solution of 8-thiabicyclo[3.2.1]octan-3-one (1.33 g, 9.32 mmol, 1 eq) in dry dichloromethane (50 mL) was added a spatula tip full of activated 4 Å molecular sieves (beads). The ketone solution was cooled to 0° C., and trimethylsilyl triflate (1.7 mL, 9.41 mmol, 1 eq) was added dropwise followed by a solution of ethyl 5-bromo-1H-indole-7-carboxylate (2.5 g, 9.32 mmol, 1 eq) in dichloromethane (25 mL). The mixture was stirred at 23° C. overnight, then was cooled to 23° C. and triethylsilane (2.3 mL, 14.4 mmol, 1.5 eq) was added in a single portion. The reaction was stirred at 23° C. for 1.5 h, then quenched by the addition of saturated aqueous sodium bicarbonate. The mixture was extracted with dichloromethane, and the combined organic extracts were dried over sodium sulfate, filtered, and concentrated. The crude product was purified by Isco Combiflash, 120 gram column, eluting with 0-30% ethyl acetate in hexanes. The ethyl 5-bromo-3-(8-thiabicyclo[3.2.1]oct-3-yl)-1H-indole-7-carboxylate was obtained as a mixture of isomers (2.38 g, 65%).
