26927-07-1Relevant articles and documents
Syntheses of Enantiomerically Pure Violaxanthins and Related Compounds
Acemoglu, Murat,Uebelhart, Peter,Rey, Max,Eugster, Conrad Hans
, p. 931 - 956 (2007/10/02)
The epoxides 16 and ent-16, prepared by Sharpless-Katsuki oxidation of 15 in excellent yield and very high enantiomeric purity, were used as synthons for the preparation of (+)-(S)-didehydrovomifoliol (45), (+)-(6S,7E,9E)-abscisic ester 46, (+)-(6S,7E,9Z)-abscisic ester 47, (-)-(3S,7E,9E)-xanthoxin (49), (-)-(3R,7E,9E)-xanthoxin (50), (3S,5R,6S,3'S,5'R,6'S,all-E)-violaxanthin (1), (3R,5R,6S,3'R,5'R,6'S,all-E)-violaxanthin (55) and their (9Z) (see 53, 57), (13Z) (see 54, 58), and (15Z) (see 60) isomers.The novel violadione (61) was prepared from 1 by oxidation with DMSO/Ac2O.By base treatment, 61 was converted into violadienedione (62), a potential precursor of carotenoids with phenolic end groups.
NATURALLY OCURING DI-CIS-VIOLAXANTHINS FROM VIOLA TRICOLOR: ISOLATION AND IDENTIFICATION BY 1H NMR SPECTROSCOPY OF FOUR DI-CIS-ISOMERS
Molnar, Peter,Szabolcs, Jozsef,Radics, Lajos
, p. 195 - 200 (2007/10/02)
From blossoms of Viola tricolor, four new naturally occuring geometrical isomers of violaxanthin (5,6,5',6'-diepoxy-5,6,5',6'-tetrahydro-β,β-carotene-3,3'-diol) have been isolated in the crystalline state.By two-dimensional 1H NMR methods, the new pigments are shown to be the 9,9'-, 9,13'-,9,15-and 9,13-di-cis isomers.Thermal and iodine-catalysed photochemical stereomutations of the new natural pigments have also been studied.Key Word Index-Viola tricolor; Violaceae; 9,9'-, 9,13'-, 9,15- and 9,13-di-cis-violaxanthins.