Dihydrocarvone

Carvestrene, or i-sylvestrene, was first prepared by Baeyer from carvone, the ketone characteristic of oil of caraway. This body, when reduced with sodium and alcohol yields dihydrocarveol, which, on oxidation is converted into dihydrocarvone. The formulae of these three bodies are as follows —... 

Hydrobrotnic acid converts dihydrocarvone into a hydrobromide, CioHjyOBr, which, when treated with cold alcoholic potash, readily loses hydrogen bromide. Instead, however, of the unsaturated substance, -dihydrocarvone, being regenerated as the result of this decomposition, a remarkable formation of a c /cZopropane ring takes place and carone is produced—... 

On oxidation with chromic acid in acetic acid solution, dihydrocarveol yields dihydrocarvone, which has a specific gravity 0 928 at 19°, and refractive index 1-47174. The dihydrocarvone from Zae o-dihydro-carveol is dextro-rotatory, and -vice versa. Its oxime melts at 88° to 89° for the optically active variety, and at 115° to 116° for the optically inactive form. 

By reduction carvone fixes 2 atoms of hydrogen on to the ketonic group, and 2 atoms in the nucleus, with the formation of dihydrocarveol, CijHjgO, whose corresponding ketone, dihydrocarvone, Cj Hj O, exists in small quantities in caraway oil. 

Dihydrocarvone, Cj Hj O, is found to a small extent in oil of caraway, and can be prepared by the oxidation of dihydrocarveol by chromic acid in acetic acid solution. The ketone has the constitution —... 

Draw the most stable chair conformation of dihydrocarvone. 

The asymmetric Michael addition of chiral nonracemic ketone enolates has most frequently been used as part of the Robinson annulation methodology in the synthesis of natural products171-172. The enolates are then derived from carbocyclic chiral ketones such as (+)-nopinone, (-)-dihydrocarvone, or (-)-3-methylsabinaketone. 

Within monocyclic ketones, a similar inversion of the migratory preference was only reported for the biooxidation of terpenones with CHMOAdneto- while (—)-dihydrocarvone is converted to the expected normal lactone, migration of the less substituted carbon center was observed for the biooxidation of antipodal (+)-dihydrocarvone, ultimately providing the abnormal lactone [185]. 

Finally, we mention here recent progress made in the Bayer-Villiger oxidation. Zeolite Sn-Beta (1.6 wt.% Sn) was found to be an excellent catalyst [25], Thus, the monoterpene dihydrocarvone gives - with Sn-Beta and H202 - exclusively the lactone (Scheme 5.7), whereas m-chloroperbenzoic acid and Ti-Beta/H202 give the epoxide as the main product. 

Ethylcyclop entanon e 3-Pentyl cyclopentanone 6-Methyl-3,5-heptadien-2-one 6-Methyl-2-cyclohexen-l-one 2,3-Dihydrocarvone Unidentified dimethylacetophenone 2-Butyrylfuran Dimethyl disulfide 2,6-Dimethylpyridine Isobutylbenzene Unidentified acetal (mol mass 154) Isobutyronitrile... 

The Hg cathode plays the role of a reducing catalyst. Electrochemical reduction of 8-bromoboman-2-one in an HMPA-Bu4NBr-(Pt/Hg) system also suggests the formation of an organomercurial intermediate that leads to the formation of dihydrocarvone as the major product [553]. 

On heating with either acid or base, the monoterpene ketone isodihydrocarvone is largely converted into one product only, its stereoisomer dihydrocarvone. 

Aldehydes in this group are as follows carvone 36, dihydrocarvone 37, isom-enthone 38, piperitone 39, pulegone (piperitenone) 40, isopulegone 41 (Structure 4.9). 

Anethum graveoleus L. Shi Luo (Dill) (fruit, young shoot) Essential oils, d-carvone, dillapiole, limonene, bergapten, umbelliprenin, camphene, dihydrocarvone, dillapiole, dipentene, isomyristicin 48-50 Carminative, stimulant. 

Reduction of 0,/3-enones. NaBH4 forms a nearly homogeneous solution in pyridine at 25°. This solution reduces /-carvone (1) at 25° (12 hours) mainly to the dihydrocarveols 2. A minor product is 3. Jones oxidation of the mixture gives dihydrocarvone (4).1 This method was first reported by Kupfer.2... 

Limonene (92) is the most widely distributed terpene in nature after a-pinene [68]. The (+)-isomer is present in Citrus peel oils at a concentration of over 90% a low concentration of the (-)-isomer is found in oils from the Mentha species and conifers [26]. The first data on the microbial transformation of limonene date back to the sixties. A soil Pseudomonad was isolated by enrichment culture technique on limonene as the sole source of carbon [69]. This Pseudomonad was also capable of growing on a-pinene, / -pinene, 1-p-menthene and p-cymene. The optimal level of limonene for growth was 0.3-0.6% (v/v) although no toxicity was observed at 2% levels. Fermentation of limonene by this bacterium in a mineral-salts medium resulted in the formation of a large number of neutral and acidic products. Dihydrocarvone, carvone, carveol, 8-p-menthene-1,2-cw-diol, 8-p-menthen-1 -ol-2-one, 8-p-menthene-1,2-trans-diol and 1 -p-menthene-6,9-diol were among the neutral products isolated and identified. The acidic compounds isolated and identified were perillic acid, /Msopropenyl pimelic acid, 2-hydroxy-8-p-menthen-7-oic acid and... 

As mentioned before, a Pseudomonas incognita was isolated by enrichment technique on the monoterpene alcohol linalool that was also able to grow on geraniol, nerol and limonene [36]. The metabolism of limonene by this bacterium was also investigated [37]. After fermentation the medium yielded as main product a crystallic acid, perillic acid, together with unmetabolised limonene, and some oxygenated compounds dihydrocarvone, carvone, carveol, p-menth-8-en-1 -ol-2-one, p-menth-8-ene-1,2-diol or p-menth-1 -ene-6,9-diol (structure not fully elucidated) and finally / -isopropenyl pimelic acid. 

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