4-Bromo-5-chloro-1H-indole

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 1.0 M solution of vinylmagnesium bromide in THF (0.13 L, 130 mmol) is added slowly to 10 g (43 mmol) of 3-bromo-4-chloro-nitrobenzene in 140 mL of THF at −40° C. The mixture is stirred at −40 C for an additional hour when aqueous NH4Cl is added. The mixture is allowed to warm to rt, and then is extracted with EtOAc. The extract is washed with brine, dried over MgSO4, filtered, concentrated, and purified twice by chromatography (33% EtOAc in hexanes) to provide 0.95 g (9.7%) of 4-bromo-5-chloro-1H-indole and 0.77 g (7.9%) of 6-bromo-5-chloro-1H-indole. Each of the indole products is separately treated with 1.1 equivalents of Boc2O and 0.2 equivalents of DMAP in MeCN. The mixtures are concentrated and the residues chromatographed (10% EtOAc in hexanes) to provide I-011 (32%) and I-012 (48%). is added is extracted with EtOAc The extract is washed with brine dried over MgSO4 filtered concentrated purified twice by chromatography (33% EtOAc in hexanes)