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New stereoisomers of quinic acid and their lactones
Author(s) -
ScholzBöttcher Barbara M.,
Ernst Ludger,
Maier Hans Gerhard
Publication year - 1991
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1991199101177
Subject(s) - quinic acid , chemistry , enantiomer , acetic acid , stereochemistry , lactone , nmr spectra database , organic chemistry , spectral line , physics , astronomy
Heating of (−)‐quinic acid [(−)‐ 1 ] at reflux temperature with 90% acetic acid/concd. H 2 SO 4 (67/1) yields a mixture of six stereoisomeric quinic acids (four meso forms and two pairs of enantiomers), four γ‐quinides (four pairs of enantiomers), and three δ‐quinides (two meso forms and one enantiomeric pair). The 1 H‐ and 13 C‐NMR spectra for most of these compounds are given. The fully trimethylsilylated derivatives of all the compounds are characterized by high‐resolution GC/MS. The existence of neo ‐quinic acid ( 6 ), its γ‐ ( 10 ) and δ‐lactone ( 12 ), of epi ‐δ‐quinide ( 13 ), of two meso ‐quinic acids, and of another γ‐quinide is reported for the first time. The structures and configurations of neo ‐quinic acid, neo ‐γ‐, neo ‐δ‐, and epi ‐δ‐ quinide are derived from their NMR spectra. All stereoisomeric quinic acids and their γ‐and δ‐lactones are also formed under the roasting conditions of coffee.