Relative signs and conformational dependence of H,H coupling constants in cyclohepta‐1,3,5‐trienes

Abstract

Abstract The 1 H NMR spectra of 7,7‐dimethyl‐3‐carbomethoxy‐cyclohepta‐1,3,5‐triene (thujic acid methyl ester), 3,7,7‐trimethylcyclohepta‐1,3,5‐triene and 7,7‐dimethoxycyclohepta‐1,3,5‐triene have been analysed in terms of chemical shifts and coupling constants. Extensive spin tickling experiments were performed to determine the relative signs of the H,H coupling constants in cycloheptatrienes. The conformational dependence of these parameters is discussed and calculated within the framework of the Pople‐Santry theory using the extended Hückel method.