Trifluoro­meth­yl derivatives of penta­cyclo­[5.4.0.02,6.03,10.05,9]undeca­ne

Three cage‐like polycyclic compounds, viz.exo‐8‐(trifluoro­meth­yl)­penta­cyclo­5.4.0.0^2,6.0^3,10.0^5,9]undecan‐endo‐8‐ol, C₁₂H₁₃F₃O, 5‐(trifluoro­meth­yl)‐4‐oxahexa­cyclo­5.4.1.0^2,6.0^3,10.0^5,9.0^8,11]­dodecan‐3‐ol, C₁₂H₁₁F₃O₂, and N‐exo‐11‐(trifluoro­meth­yl)‐endo‐11‐(trimethyl­sil­yl­oxy)­penta­cyclo­5.4.0.0^2,6.0^3,10.0^5,9]undecan‐8‐yl­idene]aniline meth­anol solvate, C₂₁H₂₄F₃NOSi·CH₄O, were obtained from the corresponding oxo derivatives by nucleophilic trifluoro­methyl­ation with (tri­fluorometh­yl)trimethyl­silane in 1,2‐dimethoxy­ethane solution in the presence of CsF. The crystal structures show that the addition of trifluoro­methanide occurs exclusively from the exo face of the polycyclic ketones. Further examination of the crystal structures, together with that of the starting penta­cyclo­5.4.0.0^2,6.0^3,10.0^5,9]undecane‐8,11‐dione, C₁₁H₁₀O₂, showed that increasing substitution at the 8‐ and/or 11‐positions in the cage mol­ecules increases the non‐bonded intra­molecular C·C distances at the mouth of the cage and changes the puckering of the five‐membered rings involving the 8‐ and 11‐positions from an envelope towards a distorted half‐chair conformation. Inter­molecular co‐operative O—H·O hydrogen bonds in the endo‐8‐ol compound link the mol­ecules into tetra­mers.