tert-Butyl N-[(11-exo-benzyl-oxy-carbonyl-8-oxopenta-cyclo-[5.4.0.0.0.0]undecane-11-endo-yloxy)carbon-yl-methyl]carbamate.

The structure of the title compound, C(26)H(29)NO(7), at 173†K has an inter-molecular N-H⋯O hydrogen bond. This is one of the few examples where a mono-ketone penta-cyclo-undecane (PCU) mol-ecule exibits hydrogen bonding in the solid state. The dihedral angles of the amide and ester groups are normal and unaffected by the cage structure. A longer than normal C-C bond [1.571†(4)†à ] was found within the cage structure.