Synthesis
1. 11.4 g of 6-bromo-N,N-dimethylnaphthalen-2-amine (Intermediate 1) was dissolved in 50 mL of anhydrous tetrahydrofuran and cooled to -78 °C under nitrogen protection. 2. 27.5 mL of n-butyllithium (2.5 M n-hexane solution) was added dropwise slowly, and the reaction was stirred at a temperature of -78 °C for 30 min. 3. 5.5 mL of N,N- dimethylformamide (DMF) to the reaction system, the reaction mixture was gradually warmed to room temperature and stirring was continued for 15 min. 4. The reaction solution was adjusted to acidic (pH<7) with 1 M hydrochloric acid and stirred for 15 min at room temperature. 5. The reaction solution was adjusted to basic (pH>7) with ammonia, and the resulting solid was collected by filtration. 6. The solid was washed several times with deionized water, and dried to afford 8.6 g of the yellow solid product 6-( dimethylamino)-2-naphthalenal in 93.5% yield.
References
[1] Patent: CN104140381, 2018, B. Location in patent: Paragraph 0057-0058
[2] Organic Letters, 2012, vol. 14, # 10, p. 2598 - 2601
[3] Patent: CN108218743, 2018, A. Location in patent: Paragraph 0040; 0045-0047
[4] Journal of the American Chemical Society, 2017, vol. 139, # 38, p. 13393 - 13403
[5] Chemistry - A European Journal, 2016, vol. 22, # 40, p. 14166 - 14170
