6602-54-6

623-50-7

371945-06-1

Using 2-chloro-3-cyanopyridine (2.00 g, 1.0 eq.) and ethyl ethanoate (1.43 mL, 1.05 eq.) as raw materials, CuI (0.05 g, 0.02 eq.) and Cs2CO3 (10.3 g, 2.2 eq.) were added to the reaction mixture under stirring conditions. The reaction system was heated to 70°C and maintained at this temperature for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature, slowly poured into deionized water (300 mL), and allowed to stand for 1 hour to promote precipitate formation. Subsequently, the precipitate was collected by filtration, ground with a solvent mixture of ether/hexane (1:1, v/v), and finally dried by azeotropic drying with toluene to afford the target product ethyl 3-amino-furo[2,3-b]pyridine-2-carboxylate (51c, 2.0 g, 70% yield).