Boron tribromide → Ethyl 3-(1-(4-bromobenzyl)-5-hydroxy-1H-benzo[d]imidazol-2-yl)-2,2-dimethylpropanoate

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Reaction Conditions

Reaction Steps

A solution of boron tribromide (2.2 mL, 1 M in DCM) was added drop-wise to a 100 mL round bottomed flask containing ethyl 3-(1-(4-bromobenzyl)-5-methoxy-1H-benzo[d]imidazol-2-yl)-2,2-dimethylpropanoate (493 mg, 1.11 mmol) and DCM (20 mL) at −78° C. The resulting solution was allowed to warm to 5° C. over 3 h and partitioned with sat. NaHCO3 (50 mL). The aqueous layer was extracted with DCM (25 mL×3). The combined organic layers were dried with sodium sulfate, filtered, and concentrated to dryness. The residue was subjected to FCC to give the title compound (370 mg, 77%). MS (ESI): mass calcd. for C21H23BrN2O3, 430.08; m/z found, 431.0 [M+H]+. 1H NMR (500 MHz, CDCl3) δ 7.43-7.39 (m, 2H), 7.25 (d, J=2.3, 1H), 6.94 (d, J=8.6, 1H), 6.88-6.84 (m, 2H), 6.77 (dd, J=8.7, 2.3, 1H), 5.32 (s, 2H), 4.07 (q, J=7.1, 2H), 3.05 (s, 2H), 1.35 (s, 6H), 1.16 (t, J=7.1, 3H).

Provenance & Evidence