Design and Synthesis of a 256-Membered π-Conjugated Oligomer Library of Regioregular Head-to-Tail Coupled Quater(3-arylthiophene)s

The rapid solid-phase synthesis of pi-conjugated oligomers is demonstrated by utilizing the parallel and the "mix-and-split" methods for the preparation of a library of 256 regioregular head-to-tail coupled oligo(3-arylthiophene)s. Chemical diversity was introduced to the growing oligomer starting from four resin-bound 3-(p-X-phenyl)-2-silylthiophenes via an iterative sequence of iodinations and Suzuki cross-coupling reactions with four 3-(p-X-phenyl)thiophene boronic esters (X = CF(3), H, CH(3), OCH(3)). Liberation from the solid support with TFA and subsequent chromatographic purification by normal-phase LC-MS provided all 256 regioregular head-to-tail coupled quater(3-arylthiophene)s.