General procedure for the synthesis of diethyl 2-(2-nitrobenzyl)malonate from 2-nitrobenzyl bromide and diethyl malonate: Potassium carbonate (9.6 g, 0.069 mol) was added to a stirring solution of diethyl malonate (8.89 g, 0.055 mol) in dimethylformamide (50 mL) under an inert atmosphere with continuous stirring for 15 minutes. Subsequently, a solution of 1-(bromomethyl)-2-nitrobenzene (10 g, 0.046 mol) in dimethylformamide (10 mL) was slowly added to the reaction mixture. The reaction mixture was stirred at room temperature for 2 h. The progress of the reaction was monitored by thin layer chromatography (TLC) to confirm complete consumption of raw materials. Upon completion of the reaction, the mixture was diluted with water (600 mL) and extracted with ethyl acetate (3 x 250 mL). The organic phases were combined, dried with anhydrous magnesium sulfate and subsequently concentrated under reduced pressure. The crude product was purified by column chromatography (silica gel: 100-200 mesh, eluent: 5% hexane solution of ethyl acetate) to give the final target compound diethyl 2-(2-nitrobenzyl)malonate (8.7 g, 63% yield).
