In this study, several alkenylated thieno[3,2-b]thiophenes were synthesized by site-selective palladium-catalyzed Heck cross-coupling reaction between 2,3,5,6-tetrabromothieno[3,2-b]thiophene and different alkenes. The structures of the products as well as the regioselectivity of the reactions were clarified by NMR and X-Ray crystal analyses. It is shown that the Heck cross-coupling of 2,3,5,6-tetrabromothieno[3,2-b]thiophene occurs selectively at the C-2 position of the fused heterocycle.