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Aquatolide Structure Elucidation

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Aquatolide is a humulane-derived sesquiterpenoid lactone isolated from Asteriscus aquaticus. The structure of aquatolide (molecular formula C15H18O3) contained an extremely rare ladderane substructure.

Asperspiropene A was first reported by He et al as the second derivative of a class of compounds containing a unique six-membered ring substructure. The molecular formula was determined from the HR-MS spectrum to be C17H26O8.

Interpreting the pattern of lines on a mass spectrum may feel overwhelming at first glance. However, with a little background knowledge of the theory behind mass spectrometry techniques, you can begin to recognize what to look for in your mass spectrum and obtain the information you need. Read more about how ACD/Labs analytical data processing tools can help.

Sesquiterpenoids are a class of compounds known to have complex structures, and due to the wide variability of these compounds, it is often challenging to determine the exact structure. Here we discuss the incorrect determination of the structure of Nordine, and later correction; as well as the elucidation of the correct structure using CASE.

Wang et al isolated a novel alkaloid lycojaponicumin (molecular formula C16H21NO4) from the alkaloidal extract in a trace amount, with a unique 5/5/5/5/6 pentacyclic ring system including two fused tetrahydroisoxazole rings. The structure was elucidated by spectroscopic methods and X-ray diffraction analysis.

Le Goff et al reported the structural characterization of two novel alkylhydrazides produced by the bacterial strain Streptomyces sp. LMA-545. The structures were elucidated using 1D and 2D 1H and 13C NMR spectroscopic analysis and high-resolution mass spectrometry. 1H–15N NMR experiments were required for full structural elucidation. Here we investigate the structure elucidation of Geralcin A ( molecular formula C15H24N2O5), one of the three isolated novel compounds.

Zhao et al isolated two novel rearranged triterpenoids from the leaves and twigs of A. chensiensis.—Spirochensilides A and B. The spectroscopic data used to elucidate the structure of Spirochensilide A (molecular formula C30H42O5), a compound containing unprecedented spiro-[5,6]system, were used to challenge ACD/Structure Elucidator Suite.

From investigating the constituents of Sarcandra glabra, P. Wang et al isolated a pair of structurally-related terpene lactones, sarglaperoxides A and B. The original experimental data related to Sarglaperoxide A (molecular formula C23H28O5) were used to challenge ACD/Structure Elucidator Suite and determine if the software could reliably elucidate this novel structure.

The authors reported the production and structure characterization of the novel sesterterpene Astellifadiene. Analysis of the 1H-1H COSY, HMBC, and NOESY correlations established the planar structure as an unprecedented 6-8-6-5-membered tetracyclic ring system. The use of NMR analyses combined with the crystalline sponge method facilitated the unambiguous determination of the Astellifadiene structure (molecular formula C25H40).

Honmura and co-workers isolated epoxyroussoenone and used calculated 13C and 1H chemical shifts, NOE data and ECD spectra analysis to define the most probable geometrical and stereoisomer, molecular formula C15H14O7.