Monoterpenoids ethers

Monosodium L-glutamate (MSG), 12 49 Monosodium phosphate (MSP), 18 833 manufacture of, 18 853, 857-858 thermal dehydration of, 18 846 Monostatic optical arrangement, 23 139 Monosubstituted boranes, 13 635-636 Monoterpenoid alcohols, 24 500-528 bicyclic, 24 527-528 monocyclic, 24 509-527 Monoterpenoid aldehydes, 24 529-536 Monoterpenoid ethers, 24 528-529 Monoterpenoid hydrocarbons,... 

Pyranoid monoterpenoid alkaloids have been reviewed, " and halogenated members of this class, (84) and (85), have already been discussed in the halogenated monoterpenoids section. " " The monoterpenoid ether (245) is reported from Artemisia tridentata-, from reported mass spectral data it may well be identical with the previously reported (and uncited) arthole (Vol. 7, p. 20), the characterization of which is still not published. Loliolide (246) is claimed to be an in vivo carotenoid degradation product in Canscora decussata additional spectral data have been published. ... 

Further papers on monoterpenoid ether juvenoids have appeared and metabolic investigation now extends to steers cf. Vol. 5, p. 7, ref. 48). ... 

The occurrence and syntheses of rose oxides, dihydrorose oxides, rosefuran, and nerol oxides, together with related compounds, have been reviewed. The structure of a cyclic monoterpenoid ether from Artemisia tridentata, which is related to the santolinyl monoterpenoids, has been confirmed (c/. Vol, 7, p. 20) as (227) and renamed artemiseole (c/. Vol. 8, p. 58 for an incorrect structural deduction).Interestingly, another new component of A. tridentata, the (3S)-diastereoisomer of (74), with formic acid yields (227) in contrast to (74) which yields the acyclic aldehyde (228). ° It is possible that some of the 31% of unidentified components in the essential oil of A. annua may correspond to these new compounds.The quinone (229) has been isolated from Lithospermum erythrofhizon, and further details on the presence of aeginetolide in Aeginetia indica have been published. 

Three monoterpenoid ethers are shown in Figure 6.19.1,8 Cineole (98), more commonly referred to simply as cineole, comprises up to 95% of the oil of Eucalyptus globulus and about 40%-50% of cajeput oil. It also can be found in an extensive range of other oils and often as a major component. It has antibacterial and decongestant properties and consequently, eucalyptus oil is used in various paramedical applications. Menthofuran (99) occurs in mint oils and contributes to the odor of peppermint. It is also found in several other oils. Rose oxide is found predominantly in rose and geranium oils. There are four isomers, the commonest being the levorotatory enantiomer of cis rose oxide (100). This is also the isomer with the lowest odor threshold of the four. 

Three monoterpenoid ethers are shown in Figure 5.19.1,8-Cineole (98), more cormnonly referred to simply as cineole, comprises up to 95% of the oil of Eucalyptus globulus and about 40-50% of... 

Whereas sesquiterpenoid hydrocarbons, with few exceptions, have inferior characteristic organoleptic properties, the ethers of this series — as far as they are known — are distinguished by outstanding odor qualities. Once the general value of these compounds as aroma components is recognized, as it is the case with the monoterpenoid ethers, the importance of this group of compounds will rapidly grow. 

Although most consumers appreciate the fieriness of chile, capsaicinoids are not perceived through odor or taste receptors but through the nociceptive pain receptors described earlier. The compounds in chile fruit that create the flavor and aroma are produced in the fruit wall. Buttery et al. [90] generated vacuum steam distilled oil from green bell pepper macerate, with well over 40 peaks on subsequent GC/MS analysis. Of these peaks, the major flavor compound associated with bell pepper aroma was 2-methoxy-3-isobutylpyrazine (Fig. 8.1). They also reported several monoterpenoids in abundance, limonene, trans- 3-ocimene, and linalool as well as other aliphatic aldehydes and ketones. The flavor composition of dried red bell pepper powder (sweet paprika) extracted with ether identified 44 key peaks by GC/MS [91]. In these dried samples the key compounds were P-ionone and several furanones. The post-harvest processing and the different fruit maturities as well as possible varietal differences are all causes for the different aromatic profiles. 

Many papers from the patent literature on pyrethroids and juvenile hormones cannot be included in this Report. Papers have reported the synthesis and activity of monoterpenoid juvenoids, including geranyl pyridyl ethers " and geranyl alkyl ethers and amines and their epoxides. Further papers in this section include a report of the potent lung toxicity of perillaketone, the observation that the malodorous water contaminant 2-methylisoborneol has the l-R-exo configuration, and that fenchyl methyl L-aspartylaminomalonate is 2 x 10" times sweeter than sucrose. ... 

The reaction of linalool with boron trifluoride etherate has been re-examined no pinenes or camphene were obtained.146 Dehydrolinalool reacts with methyl iso-propenyl ether under acidic conditions by Claisen rearrangement to give the allene (58).147 Further papers in this section include reaction of monoterpenoid alcohols with paraformaldehyde-acetic anhydride-sodium acetate,148 rearrangement of the alcohol (47 X = OH) to the oxabicycloheptane (59) and the ketone (60),149 and the rearrangement of a typical monoterpenoid vicinal hydroxy-ester to an epoxide.150... 

The structure of the monoterpenoid alkaloid alangiside (115 R = H) has been confirmed by synthesis of the O-methyl ether (115 R = Me) from secologanin and 3-hydroxy-4-methoxyphenethylamine 202 the isolation of loganic acid from the same plant (Alangium lamarckii) is consistent with biosynthetic theory. 

Kilburn has extensively studied radical cascades centered on the use of methylenecyclopropane derivatives. An addition-fragmentation process ap-parented to pathway c opened new routes for the synthesis of carbocycles. In a recent work, a Sml2-promoted cascade of propargyl ether 73 has been used to give bicyclic ether 78 with good diastereoselectivity (Scheme 24), thus providing a short route to the monoterpenoid paeonilactone B. The observed stereoselectivity in the 74 75 cyclization step was shown to be critically dependent on the presence of HMPA [84]. 

Chromatography of radiochemically homogeneous terpenoids has been reviewed useful gas-chromatographic techniques reported include the use of polyphenyl ether in g.c.-m.s. of 23 monoterpenoid hydrocarbons,the use of 3,4,5-trimethoxybenzylhydrazine for pre-column removal of aldehydes and ketones, and the resolution of some bicyclic alcohols and ketones by co-injection with a volatile chiral resolving agent. 

Tetramethylcyclohexanes.—Six new esters of ferulol (162) have been detected in Peucedanum luxurians and spectroscopic evidence is provided for the presence of (163) as an ether group in the two new coumarins, iselin and iliensin, from Seseli iliense A halogenated member of this class is discussed in the halogenated monoterpenoids section. ... 

In an extensive study of plants of the Gaillardia and Helenium species, Bohlmann and co-workers have isolated a large number of highly oxidised monoterpenoids, most of them being derived directly from thymol by oxidation at one or more of the terminal methyl groups. Compounds of type (181) have also been reported in Doronicum austriacum Jacq. Of these compounds [(177) to (183)], perhaps the last one is the most interesting, and Bohlmann has reported a synthesis of the methyl ether. 

There are several cyclic ethers derived from acyclic monoterpenoids which are of importance at lower levels in fragrances. 

Cyclopentanes, Iridoids, Monoterpenoid Alkaloids. ( —)-Bromodihydro-umbellulone (5) ( —)-isoiridomyrmecin (6) ( + )-iridomyrmecin (7) at — 150 loganin penta-acetate Rionomethyl ether bromide the rubidium... 

Monoterpenoids. It was mentioned earlier in this chapter that the semi-synthetic oxime, perillartine (1), is sweet and has some commercial use in Japan. In experiments designed to optimize the sensory attributes of the oxime sweeteners, it was found that the introduction of ether groups was advantageous, while hydroxyl groups and ring oxygen atoms tended to lower sweetness intensity and to destroy the sweet taste, respectively (16). Despite the discovery of cyclic derivatives of perillartine that are sweeter than this lead compound (20), the further development of this class of sweet substances is limited by poor water solubility and inappropriate hedonic qualities (20,21). 

Hop ether (136) and karahana ether (139) are monoterpenoid compounds which occur in Japanese hop (Shinshu-wase) 426), while the occurrence of (-h)-matatabi ether (138) and of its isomer (137) is limited to the essential oil of Actinidia polygama Franch. et Sav. (Ternstroemiaceae) 261, 716). 

An example of terpenic 1,2-epoxides is -caryophyllene oxide, also known as (-)-epoxycaryophyllene (8-31), which occurs in many essential oils. An example of terpenic 1,4-epoxides is the so-called (-l-)-dill ether, (3J ,4S,8S)-3,9-epoxy-p-menth-l-ene (8-31), which is a typical component of the essential oil of caraway (30%) and dill. An example of unsaturated 1,4-epoxides is (-l-)-menthofuran (8-31), the metabolite of ketone (-l-)-pulegone. Both compounds are components of peppermint oil (see Table 8.32, later) and are hepatotoxic. Monoterpenoid compound (- -)-l,8-cineole (also known as limonene oxide, eucalyptol or 1,8-epoxy-p-menthane 8-31) is an example of more complex structures. It is present in essential oils of many types of spices, and higher quantities are found in the essential oil of trees of the genus Eucalyptus (Myrtaceae). Trivial and systematic names of selected ethers are given in Table 8.8. 

Dipentene The terms dipentene or />-menthadienes are used to indicate a mixture of monoterpenoid hydrocarbons and ethers usually produced as by-products from processes for the manufacture of other terpenoids. The major source is as a by-product from the... 

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