The beta-arylation and -alkenylation of trifluoromethylacrylic acid with arylboronic acids and alkenes proceed smoothly under rhodium(III) catalysis. The procedures provide useful synthetic routes from readily available building brocks to beta-aryl-alpha-trifluoromethylpropanoic acid and 5,5,5-trifluoro-1,3-butadiene derivatives. Some of the obtained butadienes exhibit strong fluorescence in the solid state.