Polyphosphoric acid promoted synthesis of 10,11-dihydrobenzo[j]fluoranthen-12-one.

A straightforward synthesis of 3,8-dimethoxy-10,11-dihydrobenzo[j]fluoranthen-12-ones 1 is reported in a seven-step route from biphenyl-4,4'-diol 2 via the transformation of a double Claisen rearrangement, cross metathesis with ethyl acrylate, and polyphosphoric acid (PPA)-promoted Friedel-Crafts electrophilic benzannulation in good yields.