Regioselective Transformation of Long π-Conjugated Backbones: From Oligofurans to Oligoarenes

Oligoarenes are conjugated backbones which constitute an important class of materials, with promising applications in organic electronics and catalysis. While the synthesis of unsubstituted oligophenylenes was recently demonstrated,^[1] the introduction of monodispersed functionalized oligoarenes in a highly-selective manner remains a significant challenge.

We have previously introduced long oligofurans as new class of organic electronic materials, which are the oxygen-containing analogues of the oligothiophenes.^[2] Oligofurans were found to possess many advantages, including strong fluorescence, good field effect transistor (FET) properties, good solid-state packing and highly quinoid character compared to their thiophene analogues. Yet, the chemical reactivity or oligofurans remains largely unexplored. Unlike oligothiophenes, oligofurans can undergo Diels-Alder cycloaddition, and we were therefore interested in utilizing their reactivity for the introduction of new π-conjugated backbones.

Herein we report the conversion of long oligofurans to oligoarenes, by multiple Diels-Alder cycloadditions with aryne precursors.^[3] Consequent deoxygenation of the formed cycloadducts resulted in the formation long single step, represents a novel approach for the selective conversion of long π-conjugated systems.

References

1. A. Abdulkarim, F. Hinkel, D. Jansch, J. Freudenberg, F. E. Golling, K. Mullen J. Am. Chem. Soc. 2016, 138, 16208–16211.
2. O. Gidron, M. Bendikov Angew. Chem. Int. Ed. 2014, 53, 2546–2555.
3. S. Phatangare, O. Gidron Angew. Chem. Int. Ed. 2017, 56, 13601–13605.