ISSN:
1434-193X
Keywords:
Iridaceae
;
Tigridia pavonia
;
Iridals
;
Spiro compounds
;
Triterpenoids
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Besides numerous known iridals, which are unusual mono- or bicyclic triterpenoids of Iridaceae, lipid extracts of Tigridia pavonia bulbs contain tigridial (17), a new spirobicyclic hemiacetal with a conjugated pentaene moiety in the terpenoid side chain. The isolated natural product decomposes rapidly despite exclusion of light and oxygen. In contrast, derivatives of 17 formed by Diels-Alder reaction with 4-phenyl-3H-1,2,4-triazole-3,5-(4H)-dione (13) are stable, as are the products of a subsequent reduction with NaBH4. The products 15a,b and 16a,b of this reaction sequence were isolated and their structures elucidated by spectroscopic techniques. From these results structure 17 was inferred for the new natural product, which was confirmed by 1D and 2D NMR spectroscopy of a mixture of 11 and 17, in which the latter had been stabilized by addition of hydroquinone. The stereochemistry of 17 was deduced from 2D NOE experiments and comparison with known compounds.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
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