1. In a dry reaction flask, 4-bromo-2-ethyl-1-iodobenzene (1 equiv.) and anhydrous N,N-dimethylformamide (appropriate amount) are added.
2. Cool the reaction mixture to 0°C under inert gas protection.
3. n-Butyllithium (1.1 eq.) was added slowly, keeping the reaction temperature below 0°C and stirring for 30 minutes.
4. Warm the reaction mixture to room temperature and continue stirring for 2 hours.
5. Monitor the progress of the reaction by thin layer chromatography (TLC) to confirm complete conversion of the feedstock.
6. Upon completion of the reaction, the reaction was quenched by slow addition of dilute hydrochloric acid.
7. Extract the reaction mixture with ethyl acetate and combine the organic phases. 8.
8. The organic phase was dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. 9.
9. Purify the crude product by column chromatography to obtain 4-bromo-2-ethylbenzaldehyde.
