Palladium-catalyzed synthesis of monodisperse, controlled-length, and functionalized oligoanilines

The palladium-catalyzed amination of aryl halides, in conjunction with an orthogonal protective group scheme, forms the basis of two routes to oligoaniline precursors. One method consists of a bidirectional chain growth from a symmetric core piece, whereas the other involves a divergent-convergent synthesis of nonsymmetric fragments, followed by coupling to a symmetric core fragment. The oligoaniline precursors are soluble in a variety of common organic solvents and are easily converted to the deprotected oligoanilines. The method allows the preparation of even or odd chain lengths and the incorporation of a variety of functional groups. The synthesis of phenyl-capped heptaaniline through decaaniline, of four end-functionalized octaaniline derivatives, and of phenyl-capped 16-mer and 24-mer is described. The effects of chain length and substitution upon oligomer behavior have been investigated by electronic absorption spectroscopy and cyclic voltammetry.