Convenient Synthesis of Phosphonate Derivatives of 4-Chloro-2H-chromenes

2,4-Dichloro-2H-chromene-3-carboxylates are formed in good yield in the condensation of the appropriate precursors with SOCl 2 . These derivatives readily react with trialkyl phosphites to produce 2-phosphonate derivativesof 4-chloro-2H-chromene-3-carboxylates.