Poly‐Onio‐Substituted Quinones as Strong Electron Acceptors

The bis- and tetrakispyridino-substituted quinones 1 and 2 are stronger oxidizing agents than the known neutral systems p-chloranil 3 and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The first reduction potential of 2 is + 0.73 V (vs. Ag/AgCl)! The new oxidizing agents 1 and 2 are also interesting preparatively, because they are readily obtainable from p-chloranil 3 and the transmaination reagent 4 and are insoluble in conventional aprotic solvents for all oxidation stages (which permits simple workup).