Bromine → 5-Bromo-2,3-dihydro-7-azaindole

Participants

Reaction Steps

A solution of Br2 (18.1 mL, 56.2 g, 0.351 mol) in dry CH2Cl2 (250 mL) was added dropwise over a period of 1 h 45 min to a stirred and cooled (−5° C.) solution of 2 (42.22 g, 0.351 mol) in dry CH2Cl2 (410 mL)-pyridine (40 mL). The yellow suspension was stirred at 0° C. for 45 min and poured into a mixture of saturated aqueous NaHCO3 (800 mL) and saturated aqueous Na2S2O3 (100 mL). Methanol (10 mL) was added and the lower organic layer was separated and dried over MgSO4. The aqueous layer was extracted with AcOEt:MeOH=99:1 (7×1000 mL). These extracts were also dried with MgSO4. The organic solutions were combined and concentrated to afford 5 (59.17 g, 85%), which was used in the next step without further purification. 1H NMR (400 MHz, CDCl3) δ 3.07 (tt, J=8.4, 1.1 Hz, 2H), 3.64 (t, J=8.4 Hz, 2H), 4.47 (bs, 1H), 7.31 (m, 1H), 7.85 (dt, J=2.1, 0.9 Hz, 1H).

Provenance & Evidence