Unsymmetrically substituted 2,4-diaryl- and 2,3-diarylthiophenes were synthesized from 2,5-dichlorothiophene via 4-aryl-2-chlorothiophenes in two and four steps including Ni-mediated cross-coupling, respectively. Aluminum chloride-catalyzed reaction of 3-aryl-2-chlorothiophenes with some aromatic ethers unexpectedly led to the formation of the corresponding 2,4-isomers.

3,4′-Diaryl-, and 4,4′-diaryl-2,2′-bithienyls, new classes of mixed thiophene–arene oligomers, were synthesized from 2,5-dichlorothiophene via 4-aryl-2-chlorothiophene in three and two steps, respectively. Namely, a Friedel–Crafts type self-condensation of 4-aryl-2-chlorothiophene, followed by catalytic dechlorination, yielded unsymmetrical bithienyls. Homocoupling of 4-aryl-2-chlorothiophene using a nickel–phosphine catalyst gave symmetrical bithienyls.

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Unter Friedel‐Crafts‐Bedingungen liefern die Thiophene (I), auch in Gegenwart von Aromaten, hauptsächlich die Selbstkondensationsprodukte (III).