has been found that readily available hydroxylated cinnamic acids such as ferulic acid undergo palladium‐catalyzed decarboxylative coupling with aryl iodides and internal alkynes in a 1:1:1 manner to produce 1,4‐diarylbuta‐1,3‐dienes. The butadiene synthesis has also been achieved through the coupling of aryl halides with dienoic acids. Some of the products exhibit solid‐state fluorescence.