Functionalization of 1,2-diphenylpyrazolidine-3,5-dione with polyfluoroalkyl-containing 2- and 3-oxo esters

Fluorine-containing analogues of non-steroidal antiinflammatory drugs Tribuzone and Ketazone have been synthesized by reaction of 1,2-diphenylpyrazolidine-3,5-dione with polyfluoroalkyl-containing 3- and 2-oxo esters. Ethyl 3-(pyrazolidin-4-yl)-3-(polyfluoroalkyl)prop-2-enoates have been obtained as Knoevenagel reaction products from 3-oxo esters in the presence of l-proline. Unlike with 3-oxo esters, addition of ethyl 3,3,3-trifluoro-2-oxopropanoate under basic conditions afforded ethyl 2-(pyrazolidin-4-yl)-3,3,3-trifluoro-2-hydroxypropanoate or its salt without elimination of a water molecule.