Dimethylformamide → 1-[(Benzyloxy)methyl]-4-bromo-2-ethyl-5-formylimidazole

Participants

Reaction Conditions

Reaction Steps

A solution of 1-[(Benzyloxy)methyl]-4,5-dibromo-2-ethylimidazole (28.0 g, 75.0 mmol, Part A of example 544) in THF (300 mL) was cooled to −78° C. under nitrogen atmosphere and then added dropwise 1.6 M n-BuLi in hexane (51.75 mL, 82.5 mmol, Aldrich) over 30 mins. The mixture was stirred at −78° C. for 30 mins and then added DMF (16.5 g, 225 mmol, Aldrich) dropwise over 15 mins. The mixture was stirred at −78° C. for 30 mins. A small portion of the reaction mixture was quenched with satd. NH4Cl at −78° C. TLC (30:70 EtOAc/hexane) revealed both starting material and product showed almost identical Rf values (0.71 & 0.70) along with another minor spot at Rf=0.15. However, mass spectrum (CI—NH3) revealed absence of starting material and formation of product (m/z=325, M+2H). The reaction mixture was quenched with satd. ammonium chloride (20 mL) at −78° C. and brought to room temp. The reaction mixture was extracted with ethyl acetate (3×100 mL), washed with brine and dried with anhydrous MgSO4. The solvent was evaporated under reduced pressure to afford crude yellow oil. The crude was purified by flah column chromatography on a silica gel using dichloromethane as eluent to afford 22.6 g (93%) of colorless oil. HRMS calcd. for C14H16N2O2Br: 323.0395. Found: 323.0394 (M+H).

Provenance & Evidence