2-(2-Butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran: A New Degradation Product of 3-Hydroxy-5,6-epoxy-β-ionol

Article abstract of DOI:10.1021/jf00048a044

Identification of 2-(2-butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran diastereomers (4,5) in various leaves 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-β-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. Keywords: 2-(2-Butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran; 3-hydroxy-5,6-epoxy-β-ionol; norisoprenoid degradation; multidimensional gas chromatography-mass spectrometry