3-Bromo-4-methoxybenzaldehyde is formed by the solvent-free bromination of 4-methoxybenzaldehyde using 1,3-di-n-butylimidazolium tribromide, as a brominating reagent. 3-Bromo-4-methoxybenzaldehyde may be used in the following studies: . Asymmetric synthesis of a novel β-hydroxy-α-amino acid derivative, via Mukaiyama aldol reaction. . Synthesis of 2-(3-bromo-4-methoxyphenyl)-5-fluorobenzothiazole. . Preparation of 5-[(Z)-2-(3-bromo-4-methoxyphenyl)vinyl]-1,2-3-trimethoxybenzene. . Total synthesis of engelhardione. . Starting reagent for the synthesis of (2E)-3-(3-bromo-4-methoxyphenyl)-1-(4-methylphenyl)prop-2-en-1-one.