1-(2-Amino-4-chloro-3-fluorophenyl)-2-chloroethanone → 6-chloro-2-cyclopropyl-7-fluoro-1H-indole

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of compound 2 (4.5 g, 20.3 mmol) in toluene (50 mL) was added cyclopropyl magnesium bromide (0.5 M in THF; 102.0 mL, 50.9 mmol) at 0° C. under inert atmosphere. The reaction mixture was stirred at 0° C. for 15 min and then warmed to RT and stirring was continued for additional 1 h. After completion of the reaction by TLC, the reaction mixture was quenched with saturated ammonium chloride solution (10 mL) and extracted with EtOAc (3×75 mL). The combined organic extracts were dried over Na2SO4, filtered and concentrated under reduced pressure to obtain the crude. The crude was purified (silica gel chromatography; 1% EtOAc/Hexanes) to afford compound 3 (2.7 g, 63%) as an off-white solid. 1H NMR (500 MHz, DMSO-d6): δ 11.55 (s, 1H), 7.18 (d, J=8.5 Hz, 1H), 6.97 (dd, J=8.5, 6.5 Hz, 1H), 6.16 (s, 1H), 2.03-1.99 (m, 1H), 0.99-0.96 (m, 2H), 0.83-0.80 (m, 2H); LC-MS (ESI): 91.6%; m/z 208.1 (M−H+); (column: X Select CSH C-18, 50×3.0 mm, 3.5 μm); RT 4.32 min; 5 mM NH4OAc: ACN; 0.8 mL/min).

Provenance & Evidence