Crystal structures of (5)-()-4-[5-(furan-2-yl)-3-phenyl-4,5-di-hydro-1-pyrazol-1-yl]-4-oxobut-2-enoic acid and (5)-()-4-[5-(furan-2-yl)-3-(thio-phen-2-yl)-4,5-di-hydro-1-pyrazol-1-yl]-4-oxobut-2-enoic acid.

The title compounds, CHNO (I) and CHNOS (II), possess very similar mol-ecular geometries. In both mol-ecules, the central 1,3,5-tris-ubstituted di-hydro-pyrazole ring adopts an envelope conformation. The oxobutenoic acid fragment has an almost planar conformation [r.