Beschreibung:
<jats:p> Equipped with unique and straightforward tunable redox properties quinones find manifold applications ranging from bio-active compounds to material science.<jats:sup>[1]</jats:sup> Current state of the art synthesis still resorts to stoichiometric amounts of problematic chemical oxidizing agents and noble catalysts adding to the growing environmental strain by depletion of scarce resources.<jats:sup>[2]</jats:sup> In order to overcome this challenge, we have developed novel and scalable protocols for the synthesis of <jats:italic>para</jats:italic>-quinones applicable to readily available, inexpensive phenols and benzaldehydes.<jats:sup>[3]</jats:sup> In advancement of previous methods, the oxidation is performed free of catalyst, mediator, or terminal oxidizing agent, effectively minimizing waste. Electricity serves as a sustainable, reagent-free oxidant and enables excellent selectivity. Effortless scalability is ensured by the development of a flow protocol, which is operable at mild, ambient conditions. The novel protocols provide quinones in yields up to 99% and possess high synthetical utility through tolerance of a wealth of functional groups, including halogens, fulfilling the prerequisite for facile late-stage modification. The scalability of the reaction was proven on a gram-scale without corrosion in yield. Moreover, the versatility of the method was demonstrated by successful extension of the protocol to generate value-added quinones from the biopolymer lignin.</jats:p>
<jats:p>Literature:</jats:p>
<jats:p>[1] a) E. J. Son, J. H. Kim, K. Kim, C. B. Park, <jats:italic>J. Mater. Chem. A</jats:italic>
<jats:bold>2016</jats:bold>, <jats:italic>4</jats:italic>, 11179; b) L. A. Sazanov, <jats:italic>Nat. </jats:italic>
<jats:italic>Rev. Mol. Cell Bio.</jats:italic>
<jats:bold>2015</jats:bold>, <jats:italic>16</jats:italic>, 375.</jats:p>
<jats:p>[2] a) R. Yoshida, K. Isozaki, T. Yokoi, N. Yasuda, K. Sadakane, T. Iwamoto, H. Takaya, M. Nakamura, <jats:italic>Org. </jats:italic>
<jats:italic>Biomol. Chem.</jats:italic>
<jats:bold>2016</jats:bold>, <jats:italic>14</jats:italic>, 7468; <jats:italic>19</jats:italic>, b) K. Omura, <jats:italic>Synthesis</jats:italic>
<jats:bold>1998</jats:bold>, <jats:italic>1998</jats:italic>, 1145.</jats:p>
<jats:p>[3] F. Sprang, J. D. Herszman, S. R. Waldvogel,<jats:italic> Green Chem.</jats:italic>
<jats:bold>2022</jats:bold>, <jats:italic>24</jats:italic>, 5116–5124.</jats:p>
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<jats:p>Figure 1</jats:p>
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