Off-white crystalline powder, soluble in methanol, slightly soluble in water, insoluble in ether, soluble in dilute acids and dilute bases, from the seeds of the legume Acacia precatorius, Chickweed Abrus fruticulosus.
The general procedure for the synthesis of acacia alkaloids from L-tryptophan and iodomethane was as follows: 10.2 g of L-tryptophan was dissolved in 130 mL of dimethylsulfoxide (DMSO), and 5 g of sodium hydroxide was added in batches over a 30-minute period under nitrogen protection. After addition, the reaction system was stirred at room temperature for 1 h. Subsequently, the reaction system was cooled to 0 °C. A 30 mL solution of DMSO with 7.46 g of iodomethane was slowly added dropwise for a controlled time of 30 minutes. After the dropwise addition, the reaction was continued for 15 hours. After completion of the reaction, 50 mL of water was added to the system to quench the reaction. The reaction mixture was poured into 400 mL of ether and a large solid was precipitated and filtered. The resulting solid was dissolved in water and the pH was adjusted to 6-7 with concentrated hydrochloric acid, and the solid was again precipitated. Filtered and dried to give 8.7 g of white powdery product (80% yield, melting point 269°C). The product was analyzed by 1H-NMR, 13C-NMR, IR spectroscopy and mass spectrometry according to standard methods. The analytical results (not shown) confirmed that the resulting solid was 1-methyltryptophan with 100% purity.
[1] Journal of Organic Chemistry, 2009, vol. 74, # 1, p. 298 - 304
[2] Patent: CN105367477, 2016, A. Location in patent: Paragraph 0047; 0048; 0049
[3] Chemistry - A European Journal, 2014, vol. 20, # 46, p. 15021 - 15030
[4] Organic and Biomolecular Chemistry, 2006, vol. 4, # 2, p. 291 - 298
