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Two series of novel fully conjugated oligomers, oligothiophene-functionalized 9,9′-spirobifluorene derivatives, have been developed in this contribution. First, four 9,9′-spirobifluorene bromide derivatives (compounds 1a-d) are prepared through various synthetic routes. Oligothiophene derivatives with or without substituents are synthesized through the Grignard and Suzuki coupling reactions. The Negishi coupling reactions between oligothienylzinc chloride and various 9,9′spirobifluorene bromides with Pd(PPh3)4 as catalyst successfully produce the desired compounds, unsubstituted oligothiophene-functionalized 9,9′-spirobifluorene derivatives, compounds 2 to 4ad. Since the Negishi coupling reactions afford regioregularly head-to-tail (H-T) oligo(4-nhexylthiophene)-functionalized 9,9′-spirobifluorene derivatives in poor yields, the Suzuki coupling reactions between sodium 4-n-hexylthienyl-2-boronate 8, and various 9,9′-spirobifluorene-based bromides 1a-d and 9-16 are employed to produce highly regioregular head-to-tail oligothiophenefunctionalized 9,9′-spirobifluorene derivatives (compounds 5 to 7a-d) in very high yields. We also investigate the effect of solvents on the Suzuki coupling reactions. The structure and purity of all compounds are verified by FT-IR, 1H and 13C NMR, MS, and elemental analysis.

Solid-phase synthesis of isomerically pure head-to-tail-coupled (HT) oligo(3-hexylthiophene)s on chloromethylated polystyrene resin has been developed. Using novel sequences of iodination and Suzuki cross-coupling reaction, a series up to a dodecamer has been synthesized in high yield and purity. Removal of the conjugated oligomers from solid support as methyl esters, saponification and decarboxylation to the HT-coupled oligo(3-alkylthiophene)s could be effectively achieved. The Royal Society of Chemistry 2000.