13C NMR studies of some tricyclo[3.2.1.02,4]octanes

Abstract

AbstractThe 13C NMR chemical shifts for a series of exo‐ and endo‐3,3‐diphenyltricyclo[3.2.1.02,4]octanes are reported. Comparisons with the parent exo‐ and endo‐tricyclo[3.2.1.02,4]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[3.2.1.02,4]octyl system. Pronounced deshielding effects are seen in the endo series for C‐6 and −7 of the alkene endo‐3,3‐diphenyltricyclo[3.2.1.02,4]oct‐6‐ene, the epoxide endo‐3,3‐diphenyltricyclo[3.2.1.02,4]octan‐6,7‐exo‐oxide, and the tetracyclic exo‐3,3‐diphenyltetracyclo[3.3.1.02,406,8]nonane. The chemical shifts of C‐3 and −8 are diagnostic for endo vs. exo substitution.