Configuration and Conformation by NMR

Phomadecalins A−D and Phomapentenone A: New Bioactive Metabolites from Phoma sp. NRRL 25697, a Fungal Colonist of Hypoxylon Stromata

“…The relative stereochemistry at C-5 and C-9 was established by comparing the proton coupling constant between H-5 and H-9 with analogous couplings observed for other cyclopentenones. , In cyclopentene rings, a vicinal coupling constant of 5−6 Hz normally indicates a cis relationship, while a coupling constant of ca. 2 Hz suggests a trans relationship. − These observations have been extended to cyclopentenone rings, and a similar correlation has been observed. , Thus, in the case of 5 , the small coupling constant of 1.8 Hz is suggestive of a trans relationship between H-5 and H-9. The relative configurations at C-4 and C-11 were not determined.…”

Conformation and Configuration of Tertiary Amines via GIAO-Derived13C NMR Chemical Shifts and a Multiple Independent Variable Regression Analysis

“…In the case of 7 and 8 , using the δ pred of each carbon of both isomers as independent variables and their room-temperature time-averaged δ C as dependent variables, we find that the regression analysis correctly identifies the major configuration to be the endo structure with a 60% contribution and the minor configuration to be the exo structure with a 40% contribution (Table ). While a 3:1 endo/exo ratio was found at low temperature, the temperature difference is expected to affect the conformational equilibrium . The quality of the fit may also be affected by temperature-dependent changes in chemical shifts. , Performing a regression analysis that instead uses the experimentally determined low-temperature chemical shifts of both isomers as independent variables and the room-temperature time-averaged δ C as dependent variables yields a similar 57% endo and a 43% exo contribution (Table ).…”

Chapter 2: The Dynastic Principle in the Monarchies in the Ancient Near East

“…The conditions of the early monarchy in the Syro-Palestinian kingdoms are directly reflected in Phoenician and Aramaic inscriptions of the tenth to eighth centuries B. C. from the same region 133 139 . This difference doubtless arose from varied situations.…”