4-Hydroxy-7,8-dihydro-/-ionol

Figure 6. Structures of aglycones released from quince fruit extract after glycosidase (emulsin) treatment. 9 - 3-hydroxy-0-ionol 18 3-hydroxy- 3-ionone 19 > 3-oxo-o-ionol 20 = 3-hydroxy-7,8-dihydro-P-ionol 21 vomifoliol 22 = 7,8-dihydrovomifoliol.

Figure 1. Synthesis of 4-hydroxy-7,8-dihydro-P-ionol (4) from 4-oxo-P-ionol (2) via 4-oxo-7,8-dihydro-P-ionol (3).

Figure 4.2. Principal norisoprenoid compounds in grape and wine. (29) TDN (1,1,6-trimethyl-l,2-dihydronaphthalene) (30) P-damascone (31) P-damascenone (32) vom-ifoliol (33) dihydrovomifoliol (34) 3-hydroxy-P-damascone (35) 3-oxo-a-ionol (36) 3-hydroxy-7,8-dihydro-P-ionol (37) oc-ionol (38) P-ionol (39) a-ionone (40) P-ionone (41) actinidols (42) vitispiranes (spiro [4.5]-2,10,10-trimethyl-6-methylene-l-oxa-7-decene) (43) Riesling acetal (2,2,6-tetramethyl-7,ll-dioxatricyclo[6.2.1.01,6] undec-4-ene).

Figure 4.8. The GC/MS-EI (70eV) SCAN mode chromatogram of compounds formed by acid hydrolysis of a Raboso grape skins extract. Peak 1. frans-furanlinalool oxide peak 2. cfs-furanlinalool oxide I.S.l, internal standard (1-octanol) peak 3. (Z)-ocimenol peak 4. ( )-ocimenol peak 5. a-terpineol I.S.2, internal standard (1-decanol) peak 6. 2-exo-hydroxy-l,8-cineol peak 7. benzyl alcohol peak 8. P-phenylethanol peak 9. actinidols A peak 10. actinidols B peak 11. endiol peak 12. eugenol peak 13. vinylguaiacol peak 14. p-menthenediol I peak 15. 3-hydroxy-P-damascone peak 16. vanillin peak 17. methyl vanillate peak 18. 3-oxo-a-ionol peak 19. 3-hydroxy-7,8-dihydro-P-ionol peak 20. homovanillic alcohol peak 21. vomifoliol.

Fig. 6 Structures of glycosidically-bound aroma precursors of B-damascenone 7, theaspiranes 8, theaspirones 9, vitispiranes 10, and edulans 11, i.e. 3-hydroxy-7,8-didehydro-B-ionol 15, 4-hy

Ci3-norisoprenoids analyzed hydroxy-3-,6-D-damascone, oxo-3-a-ionol, oxo-4-/)-ionol, hydroxy-3-/S-ionol and hydroxy-3-dihydro-... 

New Natural Products Related to Carotenoids. Tobacco continues to yield volatile constituents with carotenoid-like rings, described by some authors as nor-carotenoids . New structures reported are 5-hydroxy-5,6-dihydro-3,6-epoxy-/3-ionol [carotene numbering (19)] and the related 5,8-epoxide (20). An epoxymegastigmadiene (21) has been identified in Osmanthus absolute/ The... 

Norisoprenoids detected in negligible amounts or not found in the free fraction of studied wines, were relatively abundant in the bound fraction. The Qs-norisoprenoid pattern was composed by 3-hydroxy-P-damascone, 3-oxo-a-ionol, 3-hydroxy-7,8-dihydro-(3-ionol and, in smaller concentrations, a-ionone and 4-oxo-isophorone. By contrast, (3-damascenone -detected in the free fraction in wines- was not detected in bound form as this compwimd is formed principally from the precursors 3-hydroxy-P-damascone and 3-hydroxy-7,8-dehydro-P-ionol the highest concentration of both compounds found in fraction of aroma of Rojal wines could be related to that in the free fraction Rojal wines paosented lower concentration of P-damascenone. 

Some carotenoid metabolites apparently arise during the processing of plant material [e.g., (3S, 5R, 6S)-3-hydroxy-5,6-epoxy-5,6-dihydro-P"ionol (30), 3-oxoactinidiol (31), and l-(2,3,6-trimethylphenyl)-but-2-ene-l-one (32)] are formed during curing of tobacco (Fig. 26.15). These compounds are related to p-damascenone (33) and the aromatic carotenoids. 

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