3-Methylcyclohex-2-enone derivatives as initiators of cyclisation. Part 4. Some bicyclisations

Abstract

Hydrochrysene and hydrophenanthrene derivatives (8)–(14) have been prepared by cyclisation of 2-substituted 3-methylcyclohexen-2-ones and the derived 2,3-epoxides. Cyclisation of the epoxides does not give preparatively useful yields of bicyclised compounds, the major products being monocyclised compounds. Cyclisation of the α,β-unsaturated ketones with trifluoroacetic anhydride–trifluoroacetic acid gives high yields of bicyclised products. The stereochemistry of two cyclisation products has been determined by X-ray crystallography.