Isolation 8-damascenone

The precursor structures can be elucidated by HRGC/MS and HRGC/FTTR of the acetylated derivatives or aglycons, respectively. Very recently, direct LC/MS measurement of a non-derivatized precursor glycoside of (E)-B-damascenone isolated from apples has been reported [100]. Application of such techniques on precursor fractions from wine [97, 101]... 

Isolation of Two Glucosidic Precursors of B-Damascenone From Riesling Wine. 

Figure 7. Structures of two acetylenic precursors of B-damascenone 19 isolated from Riesling wine.

Isolation of Nonvolatile Precursors of /3-Damascenone from Grapes Using Charm Analysis... 

A bioassay for the precursor compound to p-damascenone, frartj-2,6,6-trimethyl-cyclohexa-1,3-dienyl- l-but-2-ene- 1-one, found in grape skins was developed based on the generation of free p-damascenone and the sensory technique charm. Thin layer, column, and high pressure liquid chromatography were used to separate the precursor from 80 kg of grapes, Vitis labruscana, Bailey cv. Concord. There was a 22,000 fold enrichment in the precursor in 3.7 g of isolate. 

If the precursor occurs at a concentration similar to that of p-damascenone, ca. 5 ng/g in thermally processed Concord grapes, its detection during isolation requires a... 

Figure 2. The bioassay for 6-damascenone precursor isolated from Concord grapes.

Table II. Charm-based recoveries from a preparative isolation of p-damascenone precursor from 80 kg Concord grapes.

Vomifoliol (97) isolated from Rauwolfia vomitoria appears to be a degradation product of abscisic acid and possibly a precursor of theaspirone. Damas-cenone, a minor component of Bulgarian rose oil, was shown to be the cross-conjugated isomer (98) of dehydroionone. A tetrahydro-damascenone was prepared by treating a-ionone-7,8-oxide with hydrazine. ... 

Naef, R., Velluz, A., and Thommen, W. 1990. Isolation of a glucosidic precursor of damascenone from Lyceum hamifolium Mil. Tetrahedron Lett. 45 6521-22. 

Quantification of aroma-impact components by isotope dilution assays (IDA) was introduced in food flavor research by Schieberle and Grosch (1987), when trying to take into account losses of analytes due to isolation procedures. The labeled compounds have to be synthesized, the suitable fragments have to be chosen, and calibration has to be effected. A quantitative determination of ppb levels of 3-damascenone (Section 5,D.38) in foods, particularly in roasted coffee (powder and brew), was developed by Sen et al. (1991a). Semmelroch et al. (1995) quantified the potent odorants in roasted coffee by IDA. Hawthorne et al. (1992) directly determined caffeine concentration in coffee beverages with reproducibility of about 5 % using solid-phase microextraction combined with IDA. Blank et al. (1999) applied this combined method to potent coffee odorants and found it to be a rapid and accurate quantification method. They also concluded that the efficiency of IDA could be improved by optimizing the MS conditions. 

In this reaction, y ionone is converted into its oxime 19 which is oxidized to the isoxazole 20 by a special method (reaction with KJ and NaHC03 in THF/water). The compound 20 is converted into y damascenone by use of sodium in liquid ammonia in the presence of er/-butanol without isolation of the intermediate y amino ketone 21 yield 72% (based on y ionone). In this reaction, the heterocycle facilitates a 1,3-carbonyl migration within an a,y0-unsaturated carbonyl system. 

The bicyclodamascenones (576) and (577) have been isolated from Nicotiana tabacum and their structures verified from their spectra and by synthesis from P-damascenone. ... 

One of the most important discoveries recently made in the field of carotenoid aroma compounds relates to the class of damascones. Seven naturally occurring members (266) to (272) of this class are known today. The discovery of these new compounds started with the isolation of damascenone (268) from Bulgarian rose oil in 1970 120). Later, the same compound was detected in various tobacco brands 5, 110, 306), tea 491), raspberry oil 708), cooked apples 442), various grape and wine varieties 546, 549), beer 598), coffee oil 179), buchu leaf oil 283) and Roman camomile 638). 3-Hydroxy-(3-damascone (269) was shown to be an important aroma component of tobacco 108, 169, 285) in which it develops a green, rose-floral and sweet Burley-like note (556). (3-Damascone (267) was found in Burley tobacco 110) and rose oil 108), whereas a-damascone (266), accompanied by (3-compound (267) and damascenone (268), was exclusively observed in tea oil 491). Among the known cyclization products (270) to (272), the last two compounds were found in tobacco (779), while ketone (270) was detected in tea 491). 

Damascones The first member of this family to be identified was p-damascenone (343). It was isolated from the Damask rose, Rosa damascena, the oil of which contains 0.05% of it (418) and the structure was confirmed by synthesis (419). Since then, damascones... 

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