Superoxide oxidation of 1-nitropyrene-cis-dihydrodiols

Article abstract of DOI:10.1016/S0040-4020(01)86519-4

KO₂ oxidation of cis-4,5-dihydro-4,5-dihydroxy-3-nitropyrene, 1 gives the known lactone, 3-nitro-5H-phenanthro[4,5-bcd]pyran-5-one, 2. Similarly the analogous 4,5-dihydrodiol, 3, gives the known lactone, 1-nitro-5H-phenanthro[4,5-bcd]pyran-5-one, 4. While the yield of 2 is 80%, it is only 16% for 4. A study of the latter oxidation, relying especially on the use of HPLC, led to a change in the conditions that increased the yield of 4 from 16 to 88%. The change was to quench the reaction with H₂O₂ shortly after it began instead of letting it proceed, as usual, for several hours before quenching with water.