A STRUCTURE WITH THROUGH-SPACE CYCLOPROPYL PI-INTERACTION

The crystal structure determination of endo,endo-pentacyclo[7.2. 1.1(3 ,7).O-2,(8).O-4,O-6]tridec-10-en-anti-12-yl p-bromobenzoate, C20H19BrO 2 (1-OPBB), is reported. The molecule consists of norbornene with an a nti-p-bromobenzoate substituent at the methane bridge, and with an end o-norbornyl unit endo-fused to the ethano bridge. The norbornyl unit a lso has an exo-cyclopropyl ring on the two-C-atom bridge opposite the ring fusion. Interbridge steric interactions are discussed, and some c omparisons are made with other norbomenyl derivatives.