A synthesis of 4,5,6,6a,6b,7,8,12b-octahydrobenzo[j]fluoranthene

Abstract

The synthesis of the above hydrocarbon and benzo[j]fluoranthene from ethyl 3-phenylinden-1-one acetate via the useful intermediates 5,6,6a,11b-tetrahydro-7H-benzo[c]fluorene-5,7-dione, selective ketalisation of which yields a dioxolan ketone and 5,6,6a,11b-tetrahydro-7H-benzo[c]fluorene-7-one (V) is described. Reduction of the dione gives 5,6,6a,11b-tetrahydro-5-hydroxy-7H-benzo[c]fluoren-7-ol or 5,6,6a,11b-tetrahydro-7H-benzo[c]fluorene. The dione with methanolic sodium methoxide undergoes aromatization to gives 5-hydroxy-7Hbenzo[c]fluoren-7-ol, methylation of which followed by oxidation yields 5-methoxy-7H-benzo[c]fluorenone. The dioxolan ketone with sodium borohydride gives the corresponding alcohol, which with phosphorus tribromide gives (probably) 5-oxo-5,11b-dihydro-7H-benzo[c]fluorene.