6-Chloro-5-iodopyridin-2-amine (4.00 g, 15.7 mmol) and zinc cyanide (0.997 g, 8.50 mmol) were dissolved in 15 mL of N,N-dimethylformamide under argon protection. Subsequently, zinc cyanide was added, and the mixture was vigorously stirred and purged with a stream of argon for 5 min. Next, tris(dibenzylideneacetone)dipalladium(0) (0.642 g, 0.701 mmol) and 1,1'-bis(diphenylphosphino)ferrocene (0.784 g, 1.42 mmol) were added, and the reaction mixture was stirred for 10 min at 120 °C. After completion of the reaction, it was extracted with ethyl acetate and aqueous half-saturated sodium bicarbonate, and the organic phase was concentrated by filtration through silica gel. Finally, purification by silica gel column chromatography (elution gradient: cyclohexane/ethyl acetate 100/0→50/50) afforded the target product 6-amino-2-chlorocyanopyridine in a yield of 1.60 g and 66%. Mass spectrum (ESI+): m/z = 154 [M + H]+.
