Abstract:Chlorocyclopropanes (CCPs) conjugated to alk‐yn‐enes occur in a unique family of polyketide natural products from marine sponges. Synthesis of several optically enriched analogs of CCPs and measurement of their UV–vis spectra and electronic circular dichroism (ECD) spectra reveal unusually strong hyperconjugation that constrains and aligns the cyclopropyl C‐C bond with the π‐plane of the distal ene‐bond. This alignment imposes a barrier to rotation of at least 5.0 kcal·mol−1. Comparison of red‐shifted Cotton e… Show more
“…Empirical spectroscopic methods (ECD or NMR) have great advantages of simplicity and widespread application to assess the stereochemistry in molecules endowed with characteristic chromophores near chiral centers. [31][32][33][34][35] For example, the octant rule, 36,37 helicity rule 38,39 and Beecham rule. 40 Based on the structural analysis of the above guaiane-type sesquiterpenes, we hope to discover convenient rules for the rapid determination of configuration in this class of sesquiterpenes.…”
A novel C17 homo-guaiane sesquiterpene (1) and twenty-nine new guaiane-type sesquiterpenes (5−18, 23−25, 27-30, 33−40), along with ten known analogues were isolated from Daphne penicillate. Compound 1 may be derived...
“…Empirical spectroscopic methods (ECD or NMR) have great advantages of simplicity and widespread application to assess the stereochemistry in molecules endowed with characteristic chromophores near chiral centers. [31][32][33][34][35] For example, the octant rule, 36,37 helicity rule 38,39 and Beecham rule. 40 Based on the structural analysis of the above guaiane-type sesquiterpenes, we hope to discover convenient rules for the rapid determination of configuration in this class of sesquiterpenes.…”
A novel C17 homo-guaiane sesquiterpene (1) and twenty-nine new guaiane-type sesquiterpenes (5−18, 23−25, 27-30, 33−40), along with ten known analogues were isolated from Daphne penicillate. Compound 1 may be derived...
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