Transition metal free continuous flow synthesis of 2,5-diaryl furans: access to medicinal building blocks and optoelectronic materials

13 September 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The direct transformation of 1,3-dienes into valuable 2,5-diarylfurans using transition metal-free conditions is presented. By employing a simple oxidation - dehydration sequence on readily accessible 1,3-dienes, important 2,5-diarylfuran building blocks frequently used in medicinal and materials chemistry are prepared. The oxidation step is realised using singlet oxygen, and the intermediate endoperoxide is dehydrated under metal-free conditions and at ambient temperature using the Appel reagent. Notably, this sequence can be streamlined into continuous flow, thereby eliminating the isolation of the intermediate, often unstable endoperoxide. This leads to a significant improvement in isolated yields (ca. 27% average increase) of the 2,5-diarylfurans, while also increasing safety and reducing waste. Our transition metal-free synthetic approach to 2,5-diarylfurans delivers several important furan building blocks used commonly in medicinal chemistry and as optoelectronic materials, including short chain linearly conjugated furan oligomers. Consequently, we also complete a short study of the optical and electrochemical properties of a selection of these novel materials.


Continuous flow
Metal free

Supplementary materials

Supporting Information
Experimental procedures, compound characterization, crystallographic data (CCDC 2234724-8) computational figures, and copies of NMR spectra (PDF)


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