反应详情

A mixture of 4-cyanopyridine N-oxide (30 g, 0.25 mol), phosphorous oxychloride (96 ml, 0.35 mol) and phosphorous pentachloride (72 g, 0.38 mol) was refluxed at 120°-130° C. for 6 hours and then stirred at room temperature for 12 hours. The reaction mixture was slowly poured into a mixture of ice/Na2CO3 /K2CO3 and was extracted with chloroform (4×250 ml). The solvent was removed in vacuo and the residue was purified by column chromatography on silica eluting with 50% ether/hexanes to afford 8.4 g (24%) of 2-chloro-4-cyanopyridine, m.p. 69.5°-70.5° C. and 10.5 g (30%) of 3-chloro-4-cyanopyridine, m.p. 71.5°-72° C.

1. temperaturewas refluxed at 120°-130° C. for 6 hours
2. extractionwas extracted with chloroform (4×250 ml)
3. customThe solvent was removed in vacuo
4. customthe residue was purified by column chromatography on silica eluting with 50% ether/hexanes