The molecule is a phenolate anion obtained by deprotonation of the 5-OH group of nogalaviketone. It is the major microspecies at pH 7.3 (according to Marvin v 6.2.0.). It is a conjugate base of a nogalaviketone.
(1R,2S)-2,7-dihydroxy-1-methoxycarbonyl-2-methyl-4,6,11-trioxo-1,3-dihydrotetracen-5-olate