4a,9a-Epoxy-4a,9a-dihydroanthracene-1,4,9,10-tetrone: a versatile synthon in anthracyclinone synthesis

Abstract
The title compound (3a) undergoes Diels–Alder reactions with isoprene, cyclopentadiene, and cyclohexa-1,3-diene; the adducts (4) and (5a,b) can be transformed into the leucoquinizarins (6) and (7a,b) which are potentially valuable precursors of anthracyclinone analogues.