6-Benzyl-6H-pyrrolo[3,4-B]pyridine-5,7-dione was synthesized using 2,3-pyridinedicarboxylic acid and benzylamine as raw materials by the same method as described previously, and the reaction conditions were adjusted to react at 150 °C for 18-26 hours. After completion of the reaction, the crude product was purified using a 15 cm x 2.5 cm silica gel column with a hexane solution of 60-80% ethyl acetate as eluent. The yield of the purified product was recorded in Table 3. Special note: Saturated NH4Cl solution was used instead of 1 M HCl in the step of washing pyridine derivatives.
[1] Tetrahedron, 2015, vol. 71, # 48, p. 9101 - 9111
[2] Patent: CN105777750, 2016, A. Location in patent: Paragraph 0024; 0025; 0040
[3] Asian Journal of Chemistry, 2013, vol. 25, # 15, p. 8701 - 8707