Novel and efficient approach to (Z)-4-trifluoroethylidene-1,3-dioxolane derivatives via (trifluoromethyl)ethynylation of ketones and aldehydes

Perfluoroalkylated 4-trifluoroethylidene-1,3-dioxolanes 2a–p were prepared in quantitative yields from the reaction of new stable (trifluoromethyl)ethynylation reagent 1a with TBAF at −15 °C for 10 min, followed by treatment with phenyl perfluoroalkylated ketones at room temperature. The use of aldehydes under the same reaction condition afforded 1,3-dioxolanes 2q–r in good yields. The reaction of 1a with TBAF, followed by treatment with aldehydes or ketones at −15 °C for 10 min and then with trifluoroacetophenone at room temperature provided 1,3-dioxolane derivatives 2s–t in good yields. Tetrabutylammonium trifluoropropynylide [II] was treated with benzaldehyde derivatives at −15 °C for 10 min, followed by treatment with trifluoroacetophenone, to give the corresponding 1,3-dioxolanes 2u–z and 1,3-dioxines 3u–z with different reaction condition.