4- Hydroxy-/-ionol

Several new natural products based on the ionone skeleton have been isolated. Damescenone (56), jS-damascone (57) and 3-keto-a-ionol (58) were isolated from tobacco, while 4-keto-/S-ionone (59) was isolated from black tea. Treatment of dehydro-/l-ionol [alcohol from (53)] with diborane gave 3-hydroxy- -ionol (60). Photochemical oxidation gave loliolide (67) and its C-3 epimer, and the allene (61). Manganese dioxide oxidation gave an isomer of grasshopper... 

Various additives in PE (Santonox, Nonox DPPD, Neozone A, Ionol and Agerite White) were determined by conventional TLC [507]. Other additives in PE, studied by means of TLC, were Tinuvin P 120/326/327/770, Cyasorb UV531, Anti UV P (2-hydroxy-4-n-octyloxybenzophenone), Irganox 1076, Sanduvor EPU, AO-4 and Dastib 242/263 [508], TLC has also been used in the analysis of additives in polyurethanes [509,510] as well as of slip additives (ethoxylated amines and amides) in HDPE extracts... 

Fukuzumi, and M. Noguchi. Isolation of a new tobacco constituent, (3S,5R, 6S,9Zeta)-3 -hydroxy-5,6-epoxy-be ta-ionol, from Japanese domestic suifu tobacco. Agr Biol Chem 1978 42 1785-1787. 

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).

In a further series of experiments, model reactions to thermally-degrade 3-hydroxy-(5-ionol (9) were carried out. The results of these studies are represented in Figure 4. In these model reactions, compounds 5, 6 and 7 as well as unidentified isomers of 5 and 6 were all found in amounts very similar to the natural quince flavor composition obtained by SDE conditions. However, as shown in Figure 4, additional products were found comprising the megastigmatrienols 13, 14 and the tentatively-assigned bicyclic alcohol 15. These latter compounds were not detectable in quince fruit juice. Thus, the diol 9 came under question as a possible precursor. 

Figure 3. Structures of thermal degradation products of 4-hydroxy-(3-ionol (8) under SDE conditions (100°C pH 3.7). 5 = 2,2,6,7-tetra-methylbicyclo[4.3.0Jnona-4,7,9(l)-triene 10A/10B = E- and Z-megastigma-5,8-dien-4-ones 11A/11B = isomeric retro-o-ionones 12A-12D = isomeric megastigma-6,8-dien-4-ones N.I. not identified.

Figure 4. Structures of thermal degradation products of 3-hydroxy-P-ionol (9) under SDE conditions (100°Cj pH 3.7). 5 cf. Fig. 3 6 2,2,6,7-tetramethyl-bi-cyclo- [4.3.0]nona-4,9(l)-dien-8-oli 7 = 3,4-didehydro-P-ionoli 13 = megastigma-5,7,9-trien-3-oli 14 mega-stigma-4, 6,8-trien-3-ol 15 > 2,2,6,7-tetramethyl-bi cyclo[4.3.0]nona-7,9(1)-di en-4-ol.

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.

Takazawa O, Tamura H, Kogami K, Hayashi K (1982) New Synthesis of Megastigma-4,6,8-trien-3-ones, 3-Hydroxyionol, 3-Hydroxy-6-ionone, 5,6-Epoxy-3-hydroxy-6-ionol and 3-Oxo-a-ionol. Bull Chem Soc Jap 55 1907... 

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

By reaction of the Cg-hydroxyketone (3R)-58 with isopropenyl methyl ether, the acetonide 59 was obtained. Subsequent reaction with but-3-yn-2-ol (60), acetylation and dehydration gave the diacetate 61 which was reduced with sodium bis-(2-methoxyethoxy)aluminium hydride (SMEAH) to (3/ )-3-hydroxy-p-ionol (62) Scheme 15). 

Buten-2-oI, 4-(3-hydroxy-2,6,6-trimethyI-1-cycIohexen-1-yI)- 3-hydroxy-p-ionol 1364 1156, 1251,4090 ... 

Aasen, A.J., B. Kimland, and C.R. Enzell Tobacco chemistry. 18. Absolute configuration of (9R)-9-hydroxy-4, 7 -megastigmadien-3-one (3-oxo-a-ionol) Acta Chem. Scand. B27 (1973) 2104-2114. 

Fujimori, T., R. Kasuga, H. Kaneko, and M. Noguchi Isolation of 3-hydroxy-P-ionol from hurley tobacco Agr. Biol. Chem. Japan 39 (1975) 913-914. 

Buten-2-ol, 4-(4-hydroxy-2,6,6-trimethyl-1 -cyclohexen-1 -yl)- 4-hydroxy-P-ionol II.A-5... 

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

The other oxygenated Ci3-norisoprenoids identified in wine are 3-oxo-a-ionol (tobacco), 3-hydroxy-j6-damascone (tea and tobacco) and fi-damascone (tobacco and fruit). Their perception thresholds are much higher and their olfactory impact in wine negligible, in spite of relatively high concentrations in some cases. 

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... 

Of particular importance for the synthesis of carotenoids is the preparation of vinyl alcohols by the condensation of aldehydes and ketones with vinyl magnesium halides, frequently the commercially available bromides, in THF [12]. The reaction is conducted by adding a solution of the aldehyde or ketone in anhydrous THF to the vinyl Grignard reagent in THF below 0°C, and is exemplified by the preparation of the vinyl-p-ionols 20 [13] and 27 [14] from p-ionone (3) and (3/ )-3-hydroxy-p-ionone (22), respectively (Scheme 6). Table 2 lists some vinyl alcohols that have been prepared from vinyl magnesium halides. 

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