We have developed a new oxidative decarboxylation of cinnamic acids with 4-alkyl-1,4-dihydropyridines to construct C(sp³)–C(sp²) bonds in the presence of copper catalyst and dicumyl peroxide (DCP). A variety of internal alkenes have been obtained with mild conditions, broad substrate scope and excellent functional group tolerance. This method has significant potential for application by using inexpensive and stable cinnamic acids instead of alkenyl halides and nitro-olefins.