Techniques for Signal Assignment in ¹³C‐NMR Spectroscopy of Naturally Occurring Aromatic Compounds

Abstract

Abstract. Techniques of signal assignment of 13C-NMR spectra of organic compounds, and in particular those of natural origin, are reviewed. They include symmetry, chemical shift considerations, spin-spin coupling (both one-bond and long-range), spin relaxation (T" NOE), isotopic enrichment and complexing agents. Special emphasis is given to the effects of oxygenated substituents on aromatic rings.

Carbon‐13 NMR spectroscopy of some Strychnos alkaloids. Part 2

“…In this planar conformation the y -relationship between the 0methyl group and C-11 leads to a further upfield shift for this carbon, whereas C-13, lacking this relationship, is less shielded. [17][18][19] The C-10 and C-11 shifts noted in the spectra of lO,ll-dihydroxy-, 10-hydroxy-11-methoxy-and 10,ll -dimethoxy-strychnine derivatives are in agree-ment with the C-1 and C-2 shifts reported for 1,2dihydroxy-,20 l -h y d r o~y -2 -m e t h o x y -~~~~~~~~ and 1,2-dimeth~xy-benzene,'~~~~ respectively (Table 3).…”

Recent Reviews

“…Absolute configuration, 176 Activation and reaction volumes, 46 Acylation, 4-(dialkylamino)pyridines in, 34 Alkaloids, isoquinoline, 182 Lauraceae, 57 spirobenzylisoquinoline, 66 Alkanes, oxgenation with super acids, 42 Alkynes, metal complexes in synthesis, 164 natural antimycotic, 99 in pyridine synthesis, 32 Alienes, synthesis of enallenes, 105 Alumina, organic reactions on, 31 Amidyl radicals, reactivity, 123 Amino acids, oi-alkylamino, 132 codon activation, 38 industrial, 95 Angiotensin, 131 Antibiotics, acetylenic antimycotic, 99 sugar components of, 17 Aroma, naturally occurring, 80 structure and, 50 Aromatic cmpds, arene complexes, 165 biosynthesis, 124 by dehydrogenation, 43 multilayered and bridged, 161 natl occ, 13C NMR, 65 polynuclear, 3 Aromatic substitution, of nitro groups, 119 nucleophilic, Sn(ANRORC), 14 by SrnI mechanism, 11 Carbohydrates, binding by proteins, 18 boronate esters, 16 galactomannans, 19 Carbonyliron, stabilization with, 141 Catalysis, acid-base, 1 acylation, by 4-(dialkylamino)pyridines, 34 on alumina surfaces, 31 bifunctional, 101 chemiluminescence in, 84 homogeneous, 4 hydrogenation, 174 phase-transfer, 87,183 polymeric, 39 Chemiluminescence, in absorption, 84 Chlorophyll, 170,172 Cobalt catalysts in pyridine sysnthesis, 32 Complexes, alkyne-transition metal, 164 arene, 165 cation with crown cmpds, 158 chelate, stereochem. 126 of diazo cmpds, 181 organoiron, 140,141 Conductors, organic, electronic struct, 75 Conformation, angiotensin, 131 five-membered rings, 125 nucleoside, by NMR, 81 Coumarins, nat occurring, 79 Crown cmpds, 155-160 Cyanates, 180 Cy...…”