A novel substitution reaction by photoinduced electron-transfer between pyridine derivatives and alkyltin compounds

Photolysis of pyridine derivatives in the presence of SnBu4 or Sn2Bu6 leads to butyl derivatives in the α and γ positions. With 2,4-dicyanopyridine ipso-substitution of the cyano groups with the butyl groups exclusively occurs. With 4-cyanopyridine both ipso-substitution and substitution at the 2-position take place. A photo-induced electron-transfer mechanism is suggested. © 1992.