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

HRID 1776703Notes

Reaction equation

B(Br)(Br)Br.[Br:5][C:6]1[CH:32]=[CH:31][C:9]([CH2:10][N:11]2[C:15]3[CH:16]=[CH:17][C:18]([O:20]C)=[CH:19][C:14]=3[N:13]=[C:12]2[CH2:22][C:23]([CH3:30])([CH3:29])[C:24]([O:26][CH2:27][CH3:28])=[O:25])=[CH:8][CH:7]=1>C(Cl)Cl>[Br:5][C:6]1[CH:7]=[CH:8][C:9]([CH2:10][N:11]2[C:15]3[CH:16]=[CH:17][C:18]([OH:20])=[CH:19][C:14]=3[N:13]=[C:12]2[CH2:22][C:23]([CH3:29])([CH3:30])[C:24]([O:26][CH2:27][CH3:28])=[O:25])=[CH:31][CH:32]=1

Participants

Conditions

Temperature: 5 °C

Procedure

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).

Workup

custompartitioned with sat. NaHCO3 (50 mL)
extractionThe aqueous layer was extracted with DCM (25 mL×3)
dry with materialThe combined organic layers were dried with sodium sulfate
filtrationfiltered
concentrationconcentrated to dryness

Sources & evidence

ORD record: ord-943aa822a6e84757bdd1774bd93e4d29
Source dataset: uspto-grants-2016_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09265770B2

Reaction notes

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