Tetraphenyl‐substituted carotenoids with improved antioxidant and electronic conducting properties than natural carotenoids were synthesized through the formation of all‐E‐apocarotenedials (4), which were prepared by the sulfone‐mediated olefinations of the novel building blocks 7 and 3, or 8 and 9 with E‐configurations. (E)‐4‐Chloro‐2‐phenylbut‐2‐enal (10) was the key material for the syntheses.
Construction of the stable carotenoidwires with a specific conductance value is possible by the attachment of phenyl groups to the polyene chain to overcome the in vitro instability of natural carotenoids, the perfect molecular wires utilized in various biological processes. Diverse electronic natures of the substituents on the phenyl groups provide the carotenoids with tunable conductance (see figure).