Unsaturated carbon-13 nuclear magnetic resonance

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

The main structural features of yessotoxin (YTX, 1) (Figure 13.1) consist of a ladder-shaped polycyclic ether skeleton, an unsaturated terminal side chain of nine carbons, and two sulfate groups. It was first isolated from scallops, Patinopecten yessoensis, that were implicated in a DSP episode in Japan. The planar structure of YTX was elucidated by means of 2D nuclear magnetic resonance (NMR) techniques, and confirmed by fast atom bombardment mass spectrometry/mass spectrometry (FAB MS/MS) experiments " the stereochemical details were successively determined by assigning the relative and then the absolute stereochemistry. YTX has subsequently been isolated from shellfish collected along the coasts of several different countries such as Norway, Chile, New Zealand, Italy, suggesting the spread of this toxin worldwide. 

In the present wcffk, proton and carbon-13 nuclear magnetic resonance (% H . and i ) spectroscopy are used in tandem to acconplish the original goal of the chemical methods, namely, determination of the nature and level of the remaining olefinic unsaturation in order to determine cyclicity (as well as bo yield other micros tructural information). This >proach has not been reported for cyclized polyisoprene althou essentially (infrared spectroscopy plays the role pl ed by IWR in our work) the approach has recently been reported for cyclized polybutadiene. 

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