Condensation of 2-methyl-3-vinyl-?2-cyclohexenone and 3-vinyl-?2-cyclohexenone with dihydroresorcinol and methyldihydroresorcinol and cyclization of the triketones formed to hydrophenanthrene derivatives

Abstract

1. Condensation of 3-vinyl-Δ2-cyclohexenone (I) and 2-methyl-3-vinyl-Δ2-cyclohexenone (II) with methyldihydroresorcinol in the presence of alkaline agents formed the bicyclic triketones (IX) and (III), respectively. Condensation of the dienone (II) with dihydroresorcinol formed the triketone (VI) of analogous structure together with the disubstituted derivative of dihydroresorcinol (VII). 2. Condensation of the dienone (I) with dihydroresorcinol, in contrast to the previous examples, yielded an addition product for which the structure (XIV) is proposed. 3. The triketone (III) was readily cyclized by acid agents to the tricyclic diketone (IV) or the corresponding ketol (V). The triketone (IX), which has a similar structure, was not cyclized under these conditions, but the corresponding diketone (X) was obtained by condensation of the dienone (I) with methyl dihydroresorcinol under the action of piperidine phosphate. The triketone (VI) could not be cyclized. 4. In the reduction of the diketone (IV) with sodium borohydride, the unconjugated CO group was reduced selectively to form the ketol (XV).