General procedure for the preparation of 2-cyano-3-nitro-6-chloropyridine:
1. 2,6-dichloro-3-nitropyridine (5.0 g, 25.9 mmol) and cuprous(I) cyanide (2.55 g, 28.5 mmol) were mixed in N-methylpyrrolidone (19 mL).
2. the mixture was heated to 180 °C and maintained for 15 min.
3. After completion of the reaction, cooled to room temperature, the reaction mixture was poured into ice water and stirred for 10 minutes.
4. The aqueous layer was separated and the organic layer was extracted with boiling toluene followed by re-extraction with ethyl acetate.
5. The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure.
6. The residue was ground with ether and filtered to give 2-cyano-3-nitro-6-chloropyridine (1.76 g, 39% yield).
1H-NMR (CDCl3, 300MHz) data: δ 7.78 (d, J = 8.9Hz, 1H), 8.54 (d, J = 8.9Hz, 1H).
