Perfluoroacetylenephosphonates in Diels-Alder reactions: Synthesis of perfluoroalkylated heterocyclic and carbocyclic phosphonates

Article abstract of DOI:10.1016/j.jfluchem.2008.02.009

Diethyl 3,3,3-trifluoroprop-1-ynylphosphonate and diethyl 3,3,4,4,4-pentafluorobut-1-ynylphosphonate are obtained by the dehydration of the corresponding enols using P₂O₅-Et₃N system as a dehydrating agent, affording acetylenes in 50-60% yield. By the reaction of these perfluoroacetylenephosphonates with acyclic and cyclic 1,3-dienes or diene-like heteroaromatic and aromatic compounds corresponding Diels-Alder cyclo- and bicycloadducts were prepared in good yields (65-90%). The reactivity of the dienes and acetylenes which depends on their structure, as well as the regioselectivity of the reaction are established.