Ionones and Related Compounds

Heating of this in the presence of base, to prevent elimination of the alcohol, gives the ketone via an ene reaction. The prefixes a-, (3- and y- have the same meaning in the damascone series as in the ionones. 

It is obvious that the syntheses of the damascones and irones are more difficult than those of the ionones, with the inevitable result that these are much more expensive products. 

---

The mass spectra of some iron tricarbonyl derivatives of -ionone and related compounds (CVIII)-(CX) show the usual stepwise loss of CO groups from the molecular ion, but further analysis of the spectra was not attempted because of the complex nature of the ligands (36). Vitamin A... 

Several papers have reported studies of the photochemistry of ionones and related compounds, retro-y-Ionylidenemalononitrile (212) is the principal end-product from direct irradiation of /3-ionylidenemalononitrile (209) when light of >360 nm is used, but on further irradiation with light of >290 nm a new photoproduct is formed, identified from its spectroscopic properties as formally an internal [4 + 2] cycloadduct, (213).76 The isomerization of (E)-retro-a-ionone (129) and six methylated and... 

The photochemical reactions of ionones and related compounds have been studied extensively and in most cases large numbers of products have been characterized. Compounds whose behaviour on irradiation have been investigated include... 

The conversion of frans-retinyl acetate into retinoic acid in hamster organ culture,262 and of cis- and trans-rzimoxc acid into the 5,6-epoxy- and 4-oxo-derivatives and their glucuronides has been demonstrated.263 264 Strains of Aspergillus niger metabolize ionones and related compounds to oxygenated derivatives, some of which may be useful intermediates for carotenoid synthesis. The asymmetric oxidation of p-ionone to (25, 6/ ,7/ )-2,7-epoxydihydro-a-ionone (218) has been demonstrated.265 (i )-4-Hydroxy-p-ionone (219 X = OH)... 

Other Degraded Carotenoids. Several syntheses of ionones and related compounds have been described. Some of these may prove useful for end-group construction in carotenoid synthesis. Thus 4-keto-j8-ionone (126) and 3,4-dehydro-jS-ionone (127) have been prepared by condensation of the sulphone (128) with propylene oxide, followed by elimination of phenylsulphinic acid and either oxidation or dehydration. A novel method utilizes a thermal acetylenic oxy-Cope rearrangement process to prepare the ionone compounds (129—131 R = Me) and analogues (R = Et or Pr ) from cyclohex-2-enylprop-2rynols (132). 

Violets, Roses, Orris, Osmanthus, Geranium, Grapes, Vanilla, Raspberries, Passionfruit and Tea - The Chemistry of Ionones and Related Compounds... 

An important event this year is the publication of Carotenoids . This volume should be a definitive reference work on carotenoids for many years, and the scope of the book can be judged from its contents. To a large extent this volume replaces the standard work by the late Professor P. Karrer, and a review of the significance of his pioneering studies and recent developments has appeared. Other reviews have covered aspects of ionone chemistry, polyprenol quinones and related compounds,and theoretical calculations on the u.v. spectra of polyenes. ... 

Several benzopyran derivatives of potential use in the fragrance industry have been synthesized by superacid condensation of ionones, ionols and related compounds (Chapter 9, Section 2). 

Kodama, H., T. Fujimori, and K. Kato. Glucosides of ionone-related compounds in several Nicotiana species. Phytochemistry 1984 23(3) 583-585. Kodama, H., T. Fujimori, and K. Kato. A nor-sesquiterpene glycoside, rishitin-beta-sophoroside, from tobacco. Phytochemistry 1984 23(3) 690-692. 

The aroma concentrate from hoji-cha has a strong characteristic roast aroma. Hoji-cha produced about 3 times the aroma concentrate than the original ban-cha. From the basic fraction which comprised 29% of the aroma concentrate, 19 different pyrazines were identified. The neutral fraction which was 47% of the aroma concentrate contained furans and pyrroles along with the original tea aroma. In addition, ionone related compounds such as theaspirone, dihydroactinidiolide and a large amount of B-ionone were found in the neutral fraction. Table III shows the increase of furan and pyrrole content due to roasting of the ban-cha (4). 

In another study, 13-carotene was heated in aqueous medium at 90°C, 120°C and 150°C. More than 40 different compounds were found in the ether extracts by GC-MS as shown in Figure 3. Dihydroactinidiolide (sweet peachy aroma) was found in highest concentration at all temperatures studied. At 90°C, 5-6-epoxy-6-ionone (sweet, violet-like) was found in second highest quantity, while at 150°C, 2,6,6-trimethyl-2-hydroxy-cyclohexanone (green, citrusy) and 2,6,6-trimethyl-2-hydroxy-cyclohexan-1-aldehyde (floral, geraniol-like) were found in large quantity. At 120°C, these compounds were more evenly balanced than at 90°C or 150°C. A balance of ionone related compounds seem to contribute to an attractive green tea flavor. 

Carotenoid-like Compounds. Synthetic procedures for construction of the rings of ionones and other substances structurally related to carotenoids, and other procedures for the preparation and transformations of such compounds, may be useful in the carotenoid field. Thus reaction between the phenyl sulphide (143) and the... 

Kodama, H., T. Fujimori, and K. Kato Glucosides of ionone-related compounds in several Nicotiana species Phytochemistry 23 (1984) 583-585. 

Hattori, M. Watabe, A. Takahashi, K. P-Lactoglobulin protects P-ionone related compounds from degradation by heating, oxidation, and irradiation. Biosci. Biotechnol. Biochem. 1995, 59 (12), 2295-2297. 

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. 

Although the number of aroma compounds derived from acyclic carotenoids is much inferior to that of the mono- and bicyclic compounds, some of them can also be considered as breakdown products from genuine mono-, sesqui- and diterpenoids. The importance of the aliphatic isoprenoids (282) to (291) in the formation of total flavors of certain foodstuffs is not less than that of the cyclic compounds, the three methyl ketones (282), (287) and (290) which are related to the main tomato pigment lycopene were observed in tomato flavor (75). The hexahydro derivative (291) from coffee (595), jasmine oil (722) and green tea 438) is perceived as flowery and warm and can be considered as an oxidative biodegradation product of phytol and phyta-diene. 6-Methyl-3,5-heptadien-2-one (283), with a grassy and cinnamonlike aroma 438) [detected in tomato 668), the essential oil of Hama-metis leaves 383), Ceylon tea (722) and passion fruit (777)], and pseudo-ionone (288) [also isolated from passion fruit (777)] are believed to be formed from two different dehydrolycopenes. Compounds other than carotenoids, such as solanesol or squalene, can also be considered... 

Degradation of carotenes also leads to the formation of three related groups of compounds the ionones, damascones and theaspiranes. The generic structures for these materials are shown in Figure 8.20. In structures (8.55), (8.56) and (8.57), the dotted lines can be either single or... 

---