Simultaneous introduction of trifluoromethyl and λ(6)-pentafluorosulfanyl substituents using F5S-C≡C-CF3 as a dienophile.

F5S-C≡C-CF3 can be easily prepared in high yields in two steps from 3,3,3-trifluoropropyne. It is a powerful, versatile dienophile in Diels-Alder reactions. Reactions at room temperature provide the corresponding products in up to quantitative yields allowing the introduction of the pentafluorosulfanyl group and trifluoromethyl group at the 1,2 position.

CF2-containing acetylenephosphonates in heterocyclization reactions: the first synthesis of 2-difluoromethyl azaxanth-3-ylphosphonates.

Acetylenephosphonates carrying the XCF(2) group have been studied in a base-mediated heterocyclization reaction with selected 2-amino-3-formylchromones to give 2-difluoromethyl azaxanth-3-ylphosphonates. The presence of the fluorinated substituent determined the regioselectivity as well as the reactivity of this process.

Synthesis of 2-perfluoroalkyl 4H- and 2H-chromenylphosphonates mediated by amines and phosphines.

An efficient synthesis of 2-perfluoroalkyl 4H-chromen-3-ylphosphonates 4a-i (R(F) = CF(3)) and 5a-i (R(F) = C(2)F(5)) has been accomplished via regioselective cycloaddition of 2-hydroxybenzaldehydes to diethyl 3,3,3-trifluoropropyn-1-yl- and diethyl 3,3,4,4,4-pentafluorobutyn-1-ylphosphonate, using trialkyl amines or phosphines as mediators. 2H-Chromen-3-ylphosphonates 6a-i were regioselectively obtained in the presence of triphenylphosphine. A convenient method for the isomerization of 4H-chromen-3-ylphosphonates into 2H-chromen-3-ylphosphonates 6a-i (R(F) = CF(3)) and 7a-i (R(F) = C(2)F(5)) was established.