5-Aryl-3-(1,3-diphenylpyrazol-4-ylmethylene)-2(3H)-furanones (1a–c) were prepared by condensing 1,3-diphenyl-pyrazole-4-carboxaldehyde with 3-aroylpropionic acids in the presence of N,N-dimethyl(chlorosulfinyloxy)meth-animinium chloride as a cyclodehydrating agent. The reactions of these furanones with anhydrous aluminium chloride in benzene, toluene and anisole led to the formation of 4,4-diaryl-1-(1,3-diphenylpyrazol-4-yl)buta-1,3-diene-2-carboxylic acids (6) as mixtures of two geometrical (E,E- and E,Z-) stereoisomers. The unfavoured intramolecular alkylation of 1a–c compared with other furanones is discussed using Hyper Chem Professional (7) AM1 calculations.
