Synthesis
1. In a dry reaction flask, 20 g of 4-fluoroanisole was dissolved in 230 ml of anhydrous tetrahydrofuran. 2. The reaction system was cooled to -78 °C. 3. 130 ml of 2.5 M n-butyllithium tetrahydrofuran solution was added dropwise, the temperature was maintained at -78 °C, and the reaction was stirred for 2 h. 4. N,N-dimethylformamide was added to the reaction system, which was then allowed to warm naturally to room temperature. 5. Stirring continued overnight at room temperature. 6. The reaction was allowed to warm naturally to room temperature. 5. Stirring was continued at room temperature overnight. 6. After completion of the reaction, the reaction was quenched by the addition of 1 N hydrochloric acid. 7. The reaction mixture was extracted with ethyl acetate, and the organic phases were combined. 8. The organic phases were dried with anhydrous sodium sulfate, filtered, and then concentrated to afford 17 g of 2-fluoro-5-methoxybenzaldehyde. 9. The reaction was continued at room temperature for 2 hours. 10.
References
[1] Tetrahedron Letters, 1992, vol. 33, # 49, p. 7499 - 7502
[2] Patent: CN107778264, 2018, A. Location in patent: Paragraph 0025; 0026
[3] Patent: CN107698535, 2018, A. Location in patent: Paragraph 0024; 0025; 0026
[4] Patent: CN108129415, 2018, A. Location in patent: Paragraph 0024-0026
