6972-71-0

3171-45-7

(4.1) The reducing system was prepared by adding 32 mL of deionized water to 72 mL of anhydrous ethanol solution containing 12.9 g (57.17 mmol; 9.5 eq.) of SnCl2-2H2O. Subsequently, 1 g (6.02 mmol; 1 eq.) of 4,5-dimethyl-2-nitroaniline was added in batches at room temperature and under inert atmosphere. The reaction mixture was heated to reflux for 1 h. The reaction process was monitored by thin layer chromatography (TLC) (unfolding agent: ethyl acetate). After completion of the reaction, it was cooled to room temperature and the reaction mixture was poured into 120 mL of water and neutralized with NaHCO3. The tin salts and NaHCO3 were removed by filtration through filter paper. the filtrate was extracted with dichloromethane (organic phase 1) and the residual solid was continuously extracted with dichloromethane through a Soxhlet extractor for 2 days. The dichloromethane phase after Soxhlet extraction was washed once with water (organic phase 2). Organic phases 1 and 2 were combined, dried over anhydrous MgSO4, filtered and concentrated. The crude product was purified by silica gel fast column chromatography (elution gradient: cyclohexane/ethyl acetate 2/8; pure ethyl acetate; ethyl acetate/methanol 95/5). The resulting target compound (No. cs 357-1) was an orange solid in quantitative yield. rf = 0.33 (ethyl acetate). 1H NMR (CDCl3, ppm): 2.12 (s, 6H, 2 x CH3); 6.52 (s, 2H, 2 x aromatic CH). 13C NMR (CDCl3, ppm): 18.99 (CH3); 118.64 (aromatic CH); 128.02 (quaternary carbon-CH3); 132.38 (quaternary carbon-N). Mass spectrum (MS): [M + H]+ m/z = 137.1; [M + Na]+ m/z = 159.1; [M + K]+ m/z = 175.2.