Conformation and Dynamics of (−)‐β‐Caryophyllene

Abstract (−)‐β‐Caryophyllene (1) adopts three conformations in solution: αα(48%), βα(28%), and ββ(24%). The conformations were identified by an analysis of the 13 C‐ and 1 H‐NMR spectra at −87.2 and −153.8° in connection with APT, HETCOR, and COSY spectra, and subsequent NOESY experiments. The activation parameters of the conversion αα → βα were determined from a bandshape analysis of exchange‐broadened 13 C‐NMR spectra of 8‐[ methylene ‐ 13 C]‐ 1 to give Δ H ≠ = 5.9 ± 0.3 kcal/mol, Δ S  = −8.1 ± 1.8 cal/mol. · K. and Δ G = −8.3 ± 0.8 kcal/mol. The observed population ratio of the different conformers is best described by MM3.