Thiophene-perfluoroarene

Thiophene-perfluoroarene copolymers have been described (06JA2536). Absorptions in the range 334—360 were reported. 

Fluoride activation of Si-C bonds toward electrophiles has recently been exploited to synthesise alternating thiophene-perfluoroarene copolymers without using transition metal catalysis. This has the advantage of leading to products that are devoid of even traces of metal residues <2006JA2536>. Here the electrophiles are perfluoroarenes (ttF) the potential nucleophilic sites are the 2- and 5-positions of 3,4-dibutoxy-2,5-bis(trimethylsilyl)thiophene. The reaction is initiated with catalytic fluoride ion, which is regenerated with each C-C bond formed (Equation 106). 

Wang Y, Watson MD (2006) Transition-metal-free synthesis of alternating thiophene-perfluoroarene copolymers. J Am Chem Soc 128 2536—2537... 

Perfluoroarenes were also found to be highly reactive coupling partners in intermolecular direct arylation [68, 69]. A wide range of aryl halides can be employed, including heterocycles such as pyridines, thiophenes, and quinolines. A fluorinated pyridine substrate may also be cross-coupled in high yield and it was also found that the site of arylation preferentially occurs adjacent to fluorine substituents when fewer fluorine atoms are present. Interestingly, the relative rates established from competition studies reveal that the rate of the direct arylation increases with the amount of fluorine substituents on the aromatic ring. In this way, it is inversely proportional to the arene nucleophilicity and therefore cannot arise from an electrophilic aromatic substitution type process (Scheme 7). 

Perfluoroarenes can also undergo cross-dehydrogenative coupling with substituted thiophenes or furans (eq 171). ... 

Fig. 1 A few example molecules which form semiconducting crystals with high mobility, a Rubrene. b Pentacene. c Metal phthalocyanine. d One of the perfluoroarene-thiophene oligomer synthesized in T. Marks group, e Tetrathitifulvalene derivative, f PTCDI derivative...

Their reaction worked on a large library of thiophene substrates, and was even shown to arylate benzofurans and indoles in the same conditions. The reaction also tolerated a vast array of functionalities including, amides, esters, aldehydes and olefins. These perfluoroarene-thiophene compounds are being used in various electronic materials including diodes and transistors," " making Zhang s reaction a superior way to produce these materials. 

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