N-bromobutanimide → 2-bromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazole-4-carbonitrile

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Reaction Conditions

Reaction Steps

A 22-L, four-neck, round-bottom flask equipped with a mechanical stirrer, a temperature probe, and a condenser with a nitrogen inlet was charged with a mixture of 1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-4-carbonitrile and 3-(2-trimethylsilanyl-ethoxymethyl)-3H-imidazole-4-carbonitrile [600 g, 2.69 mol, as prepared in the previous step) and carbon tetrachloride (1.8 L). Agitation was initiated and the mixture was heated to 60° C. At this point N-bromosuccinimide (502 g, 2.82 mol) was added in several portions over 30 min, which resulted in an exotherm to 74° C. The reaction was allowed to cool to 60° C. and further stirred at 60° C. for 1 h. The reaction was allowed to cool slowly to ambient temperature and the resulting slurry was filtered and the filtrate washed with satd NaHCO3 solution (4.0 L). The organics were passed through a plug of silica gel (8×15 cm, silica gel; 600 g) using 2:1 heptane/ethyl acetate (6.0 L) as eluent. The fractions containing the product (based on TLC analysis) were combined and concentrated under reduced pressure to give a crystalline light yellow solid, which was then filtered and washed with heptane (500 mL) to give the title compound as a crystalline white solid [593 g, 73%). The 1H and 13C NMR spectra were consistent with the assigned structure and showed no evidence of the minor regioisomer.

Provenance & Evidence