Monoterpenoids ketones

Monoterpenoid ketones, 24 536-541 Monoterpenoids, 24 468, 470, 472, 484-541 Monothiocarboxylic acids, 23 739 Monotropic phase transitions, 15 101 Monounsaturated fatty acids, 10 830 Monounsaturated olefins, hydrogenation of, 26 879-880 Monovinylacetylene, 1 230 Monsanto acetic acid process, 19 646 Monsanto adiponitrile process, 17 236 Monsanto aluminum chloride-based Alkylation process, 23 333 Monsanto Prism separator, 16 21 Monsanto process (Lummus-UOP Classic process), 16 74 23 339, 341 Monsanto-Washington University collaboration, 24 390, 400-401 Montanic acid... 

Recently, the biotransformation of (+)-pulegone and other monoterpenoid ketones, like (-)-piperitenone, (+)- and (-)-carvone, (-)-menthone and (-)-verbenone by yeasts and yeast-like fungi was also... 

As an example of the co-existence of systematic, semi-systematic and trivial names, we could look at the monoterpenoid ketone, carvone. Carvone occurs in both enantiomeric forms in nature, the laevo-form in spearmint and the dextro-form in caraway. The trivial name carvone is derived from the Latin name for caraway, Carum carvi. The basic carbon skeleton is that of l-isopropyl-4-methylcyclohexane. This skeleton is very common in nature and is particularly important in the genus Mentha, which includes various types of mint, since it forms the backbone of most of the important components of mint oils. The skeleton has therefore been given the name p-menthane and the numbering system used for it is shown in Figure 1.3. Therefore, any of the following names may be used to describe the same molecule carvone, p-mentha-1,8-dien-6-one and 1 -methyl-4-(l-methylethenyl)cyclohex-l-ene-6-one. To classify it, we could say it was an unsaturated ketone of the /7-menthane family of monoterpenoids. 

Monoterpenoid ketones are cyclic compounds in which a carbonyl group is bonded to two carbon atoms. They are produced by oxidation of alcohols and are relatively stable molecules. Monocyclic ketones such as pulegone contain a single carbon ring while bicyclic ketones like camphor contain two fused rings. Most ketones have the suffix one . 

Figure 5.21 shows some of the commoner monoterpenoid ketones found in essential oils. Both enantiomers of carvone are found in nature, the (R)-(-)- (usually referred to as /-carvone) (105) being the commoner. This enantiomer provides the characteristic odor of spearmint (Mentha cardiaca, Mentha gracilis, Mentha spicata, and Mentha viridis), the oil of which usually contains 55-75% of /-carvone. The (5)-(+)-enantiomer (106) is found in caraway at levels of 30-65% and... 

Beside reduction of the carbonyl group, which often constitutes the unique biotransformation observed, some monoterpenoid ketones such as ( )-piperitone (150) [180], (R)-pulegone (151) [181,182], (3- (152) [183] or a-thujone (153) [184] are hydroxylated in... 

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. 

G.l.c. papers of interest include the classification of 22 acyclic monoterpenoid alcohols according to retention indexes, resolution of cyclic ketones [e.g. ( )-menthone, ( )-isomenthone] as diethyl (+)-tartrate acetals, and the use of lanthanide shift reagents to resolve non-terpenoid racemic epoxides.The occurrence and prevention of monoterpenoid hydrocarbon isomerization during silica gel chromatography has been examined and the separation of monoterpenoids and sesquiterpenoids by gel permeation chromatography is reported. Monoterpenoid hydrocarbons have been selectively extracted from essential oils using dimethylsilicone. ... 

Selective catalytic hydrogenation with chromium-promoted Raney nickel is reported (e.g. citral and citronellal to citronellol) NaHCr2(CO)io and KHFe(CO)4 reduction of a/3-unsaturated ketones (e.g. citral to citronellal) has been described (cf. Vol. 7, p. 7). The full paper on selective carbonyl reductions on alumina (Vol. 7, p. 7) has been published." Dehydrogenation of monoterpenoid alcohols over liquid-metal catalysts gives aldehydes and ketones in useful yields. ... 

Different methods of computer-matching the mass spectra of 122 monoterpenoids give the best results when six to eight of the most intense peaks are matched.21 The mass spectral fragmentation patterns of various bicyclic ketones of the thujane and carane series, and of their deuteriated [e.g. (6 X = D)] analogues, did not produce any generalizations on the fragmentation patterns or on the deuterium content.22... 

The analysis of essential oils which contain monoterpenoids has contributed many papers to the literature this year a disturbing number of analyses are trivial and furnish little that is new. The validity of the natural occurrence of minor components can be questioned in the light of isolation technique linalyl acetate yields eleven monoterpenoids on steam distillation.87 Analyses of interest are the major component (58%) of the steam-volatile leaf oil of Zieria aspalathoides is (—)-car-3-en-2-one 88 (+)-2,6-dimethyloct-7-en-4-one is the major component (97%) in Phebalium glandulosum subsp. glandulosum 89 major components in Achillea millefolium essential oil (isolated by steam distillation ) are sabinene and artemisia ketone,90 which is incorrectly named by the authors as isoartemisia ketone (possibly from... 

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... 

Cyclohexane monoterpenes are a chemically diverse group of monoterpenoids that occur in the plant kingdom mainly as hydrocarbons, alcohols, ketones, aromatic hydrocarbons, and phenols (Fig. 5). The saturated hydrocarbon trans-p-menthme (El) is a constituent of the oil of turpentine and the resin of pine (Pinaceae) trees. Its unsaturated analogs, namely (i )-(- -)-limonene (E2) [present in oil of orange (Citrus aurantium) and mandarin (Citrus reticulata, Rutaceae) peel oil] a-terpinene (E3) and terpinolene (E4) in some Citrus, Juniperus, Mentha and Pinus species (i )-(-)-a-phellandrene (E5) in Eucalyptus phellandra (Myrtaceae) and (5)-(- -)-3-phellandrene (E6) in water feimel (Phel-landrium aquaticum, Umbelliferae), are components of many plant volatile oils. The rich chemical diversity of cyclohexane monoterpene alcohols is apparent from the natural occurrence of all four pairs of / -menthan-3-ol enantiomers, for... 

Cyclopentane bicyclic monoterpenoids that occur in the plant kingdom belong to three major skeletal types camphane, iso-camphane, and fenchane (Fig. 7). Camphane-type terpenoid alcohols, (+)-bomeol (Gl) and (—)-isobomeol (G2), have been isolated from Cinnamomum camphora (Lauraceae) and Achillea filipendulina (Asteraceae). A ketone derived from these, (-h)-camphor (G3), is found in the camphor tree Cinnamomum camphora) and in the leaves of rosemary Rosmarinus officinalis) and sage Salvia officinalis, Labiatae). Camphene (G4) and its enantiomer with the isocamphane carbon skeleton are known to occur in the oils of citronella and turpentine. Fenchane-type bicyclic cyclopentane monoterpenoids are commonly found in plants as their ketone derivatives. (—)-Fenchone (G5) occurs in the tree of life Thuja occidentalis, Cupres-saceae). Its enantiomer, (+)-fenchone (G6), has been isolated from the oil of fennel Foeniculum vulgare, Umbelliferae). 

The Ci5 terpenoids known as sesquiterpenoids are the most chemically diverse group of terpenoids known in nature. Like monoterpenoids, many sesquiterpenoids contribute to the flavor and fragrances of a variety of plant products. To date about 10,000 sesquiterpenoids are known (32), and in the plant kingdom they commonly occur as hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, lactones, and oxiranes. The acyclic sesquiterpene hydrocarbons a- and p-farnesenes (HI and H2, respectively) (Fig. 8) are constituents of the oils... 

Unexpected results have come to light bearing on monoterpenoid biosynthesis (Chapter 1). Banthorpe s group have shown that in the formation of the thujane and camphor skeletons, activity from labelled mevalonic acid can appear predominantly in the C5 unit supposedly derived from isopentenyl pyrophosphate and only to a minor extent in the dimethylallyl pyrophosphate-derived portion. Banthorpe has also presented evidence for a chrysanthemyl intermediate, analogous to presqualene alcohol, in the biosynthesis of artemesia ketone. 

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