Synthesis of symmetrical carotenoids by a two-fold Stille reaction

beta-Carotene 1 and (3R,3'R)-zeaxanthin 2 have been stereoselectively prepared in a highly convergent fashion by a 2-fold Stille cross-coupling reaction. The C(12-)pentaenylbis-stannane 8 is the central lynchpin that connects two units of the terminal C-14-iodides 9 and 17 to afford 1 and 2, respectively.