A series of 2-phenylpropionic acids substituted with a C₂-C₆ alkenyl group at the para position was synthesized by hydrolysis of the corresponding esters prepared by a new nickel-catalyzed coupling reaction of aryl Grignard reagents and 2-bromopropionic acid ester. Among the 2-(4-alkenylphenyl)propionic acids thus obtained, 2-[4-(2-metyl-1-propenyl)phenyl]propionic acid showed the most potent antiinflammatory activity in the carrageenin edema test, while 2-[4-(3-methyl-2-butenyl)phenyl]propionic acid showed almost the same activity and significantly lower toxicity in comparison with those of ibuprofen.