Boron trifluoride etherate → 5-Bromo-3-[1-(2,6-dichloro-3-fluorophenyl)ethyl]-1H-pyrrolo[2,3-b]pyridine

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Reaction Steps

(5-Bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)-(2,6-dichloro-3-fluorophenyl)methanol (5.05 g, 12.9 mmol) was dissolved in anhydrous THF (100 mL). To this solution was added BF3.OEt2 (10.66 mL, 6.5 eq.) at −78° C. The resulting solution was stirred for 10 min at the same temp before a solution of ZnMe2 (35.60 mL, 5.5 eq., 2 N in toluene) was added. The resulting mixture was allowed to warm up to rt in 1 h. The solution was then stirred at 65° C. for 3.5 h. Reaction was monitored by LC-MS. After achieving >95% conversion, the reaction was allowed to cool down to rt. Then it was further cooled down to −78° C. and quenched by adding sat. aq. NH4Cl solution (10 mL). The mixture was slowly warmed up to rt. Solvents were removed under reduced pressure. To the residue was added aq. NaHCO3 solution and the mixture was then extracted with CHCl3 (100 mL×4). The organic extracts were combined, dried (Na2SO4), and concentrated in vacuo to give a crude residue which was purified by flash chromatography (eluent: 10% ethyl acetate in hexane). 1H NMR (400 MHz DMSO-d6): δ=11.85 (br. s., 1H), 8.21 (d, J=2.0 Hz, 1H), 7.49-7.59 (m, 2H), 7.41 (dd, J=8.8, 8.6 Hz, 1H), 7.30 (d, J=2.0 Hz, 1H), 5.11 (q, J=7.3 Hz, 1H), 1.80 (d, J=7.3 Hz, 3H); 13C NMR (100.6 MHz, DMSO-d6): δ=156.74 (JCF=247.4 Hz), 146.91, 142.24, 141.02, 129.37, 127.56, 125.98, 121.73 (JCF=19.8 Hz), 120.18, 115.98 (JCF=23.4 Hz), 113.62, 109.99, 33.53, 15.94. MS (ES+): m/z=386.93, 388.91, 390.89 [MH+]. HPLC: tR=4.17 min (ZQ3, polar—5 min).

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