Half-Chair Conformation of trans-1,4-Dimethyl-7,7-diphenylbicyclo[4.1.0]hepta-2,5-dione

The structure of the title compound, C₂₁H₂₀O₂, was determined by X-ray analysis. The results revealed that the 2,5-dioxocyclohexane skeleton is in a half-chair conformation, with torsion angles C(2)-C(1)-C(6)-C(5) -1.5 (3) and C(2)-C(3)-C(4)-C(5) -36.5 (3)° on account of the fused cyclopropane ring, which locates the 4-methyl group in an equatorial position. The plane of the endo-phenyl group was also found to be essentially parallel to the fused C(1)-C(6) bond.

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