2-(2-Butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran: a new degradation product of 3-hydroxy-5,6-epoxy-beta ionol
1994
Neugebauer, W. | Winterhalter, P. | Schreier, P.
Identification of 2-(2-butenylidene)-3,3-dimethyl-5-(2-oxopropyl) tetrahydrofuran diastereomers (4, 5) in various leaves [stinging nettle; sloe tree; strawberry; vine (Riesling); sweet silique (Bunias orientalis)] was achieved by comparison of HRGC retention and spectral (MS; vapor phase FTIR) data with those of synthetic references. Model experiments revealed their acid-catalyzed formation from 3-hydroxy-5,6-epoxy-beta-ionol that was present in glycosidically bound form in the above mentioned leaves. Assignment of the isomers 4a/4b and 5a/5b was established by NOE experiments. Enantiodifferentiation carried out by on-line coupled multidimensional gas chromatography-mass spectrometry revealed the occurrence of enantiomerically pure 5S enantiomers 4b/5b in the natural sources. A pathway for the selective formation of 4b/5b in nature is proposed.
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