c) The synthesis of 2-ethyl-6-methylbenzaldehyde was carried out with reference to the method described in Synthesis 1999, 2138-2144. At 0 °C, 3.20 g (15.3 mmol) of butyl-[1-(2-chloro-6-methylphenyl)-methyl-(E)-ylidene]-amine was dissolved in 30 mL of tetrahydrofuran and 0.19 g (1.53 mmol) of manganese(II) chloride was added. Subsequently, 15.3 mL (30.5 mmol) of an ether solution of 2M ethylmagnesium chloride was added slowly and dropwise while maintaining the temperature of the reaction mixture at 5-10°C. The reaction was completed with stirring. After the dropwise addition was completed, the reaction mixture was continued to be stirred for 90 minutes, during which the temperature was raised to 50 °C (exothermic reaction). Upon completion of the reaction, the reaction was quenched by dropwise addition of water and subsequently diluted with ethyl acetate. The mixture was washed sequentially with water and saturated brine, the organic phase was separated, dried over anhydrous sodium sulfate, filtered and concentrated in vacuum. The residue was purified by fast chromatography (silica gel, ethyl acetate/heptane gradient) to give 1.88 g (83% yield) of 2-ethyl-6-methylbenzaldehyde as a yellow oil.1H-NMR (CDCl3): δ 1.26 (3H, t, CH3), 2.60 (3H, s, CH3), 2.98 (2H, q, CH2), 7.09 (1H, d , ArH), 7.12 (1H, d, ArH), 7.35 (1H, dd, ArH), 10.6 (1H, s, CHO).
![1-Butanamine, N-[(2-chloro-6-methylphenyl)methylene]-, [N(E)]-](/CAS/20211123/GIF/945408-08-2.gif)
