The cyclization of acetoacetic ester (I) with crotonaldehyde (II) by means of Na and 2-(trimethylsilyl)ethanol (A) in ethyl ether gives the cyclohexenone carboxylic ester (III), which is hydroxylated by means of NaH, Tbdms-OTf and dimethyldioxirane (DMDO) in DMF, yielding the alpha-hydroxy compound (IV). The bromination of (IV) with NBS and AIBN, followed by treatment with Ag2CO3 in acetone/water, affords the diol (V), which is oxidized with DMP to the cyclohexenedione (VI). The cyclization of (VI) with benzocyclobutane (VII) in hot toluene provides the tricyclic dione (VIII), which is aromatized by means of CSA in pyridine/MeOH, furnishing the dihydroanthraquinone (IX). The Grignard condensation of (IX) with isoamylmagnesium bromide (X) in THF gives the adduct (XI), which is finally desilylated by means of TAS-F in THF.