[C:1]([C:3]1[S:4][C:5]([CH2:8]O)=[CH:6][CH:7]=1)#[N:2].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(Br)(Br)(Br)[Br:30]>C1COCC1>[C:1]([C:3]1[S:4][C:5]([CH2:8][Br:30])=[CH:6][CH:7]=1)#[N:2]To a solution of 2-cyano-5-(hydroxymethyl)thiophene (6.0 g, 43 mmol) in THF (50 mL) was added triphenylphosphine (15.7 g, 47 mmol) and carbon tetrabromide (12.3 g, 47 mmol). After stirring overnight under nitrogen atmosphere at room temperature, the solvent was removed in vacuo and the residue was dissolved in chloroform, then adsorbed onto silica gel and loaded onto a silica gel column. The product was eluted using an ethyl acetate/hexanes gradient. Fractions containing pure product (as judged by TLC) were pooled and concentrated in vacuo to give 6.5 g (75%) of 2-cyano-5-(bromomethyl)thiophene.
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