Treatment of acetyl- 1,4-benzoquinone with isoprene gave the corresponding
regioselective adduct (I). Rearrangement of the adduct (1) in pyridine and
methanol gave 2-acetyl-5, 8-dihydro-6-methyl- 1,4-dihydroxynaphthalene (2).
Silver oxide oxidation of the rearranged product (2) gave 2-acetyl-5,8-dihydro-
6-methyl- 1,4naphthalenedione (3). Regioselective addition of trans-piperylene
to this compound (3) gave the c&esponding adduct (4). Treatment of the
resulting cycloadduct (4) with manganese dioxide gave the regiospecific 1,6-
dimethyl-9, 10-anthracenedione (5). Each of the foregoing reactions proceeds in
high yield