Preparation of halo enol phostones by reaction of acetylenic phosphonate monoesters with (bis-collidine)halo hexafluorophosphate

Reaction of non-conjugated acetylenic phosphonate monoesters with (bis-collidine) bromo and iodo hexafluorophosphates was found to lead to the formation of halo enol phostones. Depending on the size of the heterocyclic compounds formed (6–8-membered compounds), endo or a mixture of endo and exo cyclization products were obtained.