A method for catalytic conversion of C(aryl)-C(alkenyl) bonds in styrene derivatives to new C-C bonds is developed. In the presence of a rhodium catalyst, the alkenyl groups of styrenes bearing a pyrazolyl directing group were efficiently converted to other carbon substituents upon reacting with various alkenes including styrenes, aliphatic alkenes, and allyl alcohols. It is also indicated that the C-C bond cleavage proceeded via a hydrometalation/beta-carbon elimination pathway.