Voacanga alkaloids. 16. Carbon-13 nuclear magnetic resonance spectroscopy of naturally occurring substances. 43. Carbon-13 nuclear magnetic resonance analysis of bis-indoline alkaloids of two voacanga species

The Use of Carbon-13 Nuclear Magnetic Resonance Spectroscopy in Natural Products Chemistry

“…On the basis of this data set, the structures of related alkaloids vobtusine 3-lactam, vobtusine 3-lactam N~-oxide, voafolidine, voafoline, isovoafoline, folicanginine, subsessiline and subsessiline lactone could be determined (195). Oxaline, a novel alkaloid from Penicillium oxalicum, to which structure (731) was assigned, has been thoroughly studied by 13C n. m. r. spectroscopy (30).…”

“…In contrast, (196) and (197), formed by dehydration of (194) and (195), resp., turned out to be spectroscopically homogeneous. In contrast, (196) and (197), formed by dehydration of (194) and (195), resp., turned out to be spectroscopically homogeneous.…”

“…Since one of the minor constituents occurred as a small impurity, its spectrum was obtained by subtraction of the spectrum of the pure compound. The BC PND spectrum of (194) and (195) afforded two sets of lines each indicating The BC PND spectrum of (194) and (195) afforded two sets of lines each indicating…”

Tabernaesines A–I, Cytotoxic Aspidosperma–Aspidosperma-Type Bisindole Alkaloids from Tabernaemontana pachysiphon

“…The 13 C NMR spectrum ( Table ) revealed 42 carbon signals that included two methyls, 12 methylenes, 15 methines, 11 nonprotonated carbons, one amide carbonyl carbon (δ C 171.5), and one ester carbonyl carbon (δ C 168.2), respectively. Among them, one ester carbonyl carbon and two nonprotonated carbons (δ C 164.5, 93.5) were readily assigned as a β-anilinoacrylate moiety . The 1D NMR data showed 1 to be an aspidosperma–aspidosperma bisindole alkaloid that was closely related to voafoline ( 10 ), except for the presence of an amido carbonyl carbon (δ C 171.5).…”

Synthesis and characterization of amino acid-modified adsorption resins and their adsorption properties in the purification of tabersonine from Voacanga africana seeds

“…[3][4][5] Among them, tabersonine, a well known alkaloid, was isolated from Voacanga seeds. 1,6 Its structure and properties have been disclosed in the prior art treatise. 7 It is known to have an indole-like structure and is related to the Vinca alkaloids.…”