Symmetrical diaryl beta-diketones 1c,d as dibenzoylmethane derivatives were obtained from 2,3-dihalo-1,3-bis(4-aryl)-1-propanone and sodium methoxide as yellow or white crystals in 22% or 51% yield. The beta-diketones 1c,d combine with oxalyl chloride to yield 4-(3,4-dimethoxybenzoyl)-5-(3,4-dimethoxyphenyl)furan-2,3-dione (2c) and 4-(4-methylbenzoyl)-5-(4-methylphenyl)furan-2,3-dione (2d), respectively, which are novel starting materials for synthesizing many heterocycles. Thermal decomposition of 2c,d is supposed to occur by the ring opening of compound 2 followed by dimerization of the intermediate alpha-oxoketene resulting in the pyran-4-ones 3c,d. Alternatively, pyran-4-ones 3c,d were obtained by thermolysis of 2c,d in xylene in presence of 1c and 1d, most likely by trapping the diacylketene intermediates. All newly synthesized compounds were characterized by elemental analysis, IR, H-1 and C-13 NMR spectral data. All were compared with their previous analogues.