Practical access to 1,3,5-triarylbenzenes from chalcones and DMSO

An unprecedented practical access to 1,3,5-triarylbenzenes has been developed from chalcones with DMSO as a reaction partner and solvent. This procedure involved a base-promoted addition of dimethyl sulfoxide anion to chalcones, followed by an aldol-type cyclization. The results of the isotopic labeling experiments indicated that one C of the central benzene ring was derived from DMSO. In comparison to the reported methods of preparing triarylbenzenes, this protocol could simultaneously provide C-3-symmetric and C-3-unsymmetric triarylbenzenes under obviously milder reaction conditions (60 degrees C, 5 h). The diverse functionalized triarylbenzenes were obtained in up to 82% yields for 24 examples.