13 C NMR studies of some tricyclo[3.2.1.0 2,4 ]octanes

The 13 C NMR chemical shifts for a series of exo ‐ and endo ‐3,3‐diphenyltricyclo[3.2.1.0 2,4 ]octanes are reported. Comparisons with the parent exo ‐ and endo ‐tricyclo[3.2.1.0 2,4 ]octanes and with bicyclo[2.2.1]heptanes show that most of the chemical shifts are additive. Substituent effect constants are presented for the tricyclo[3.2.1.0 2,4 ]octyl system. Pronounced deshielding effects are seen in the endo series for C‐6 and −7 of the alkene endo ‐3,3‐diphenyltricyclo[3.2.1.0 2,4 ]oct‐6‐ene, the epoxide endo ‐3,3‐diphenyltricyclo[3.2.1.0 2,4 ]octan‐6,7‐ exo ‐oxide, and the tetracyclic exo ‐3,3‐diphenyltetracyclo[3.3.1.0 2,4 0 6,8 ]nonane. The chemical shifts of C‐3 and −8 are diagnostic for endo vs. exo substitution.