Carvone from carveol

Di-hydro Carveol, Di-hydro Carvone.—Di-hydro carveol, the other important menthen-ol, is present in kummel oil, together with the corresponding ketone, di-hydro carvone, from which it may be obtained by reduction. This ketone is the di-hydrogen addition product of a mentha-di-ene ketone known as carvone which we shall presently consider. 

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... 

The fungal bioconversion of limonene was further studied [82]. Penicillium sp. cultures were isolated from rotting orange rind that utilised limonene and converted it rapidly to a-terpineol. Bowen [83] isolated two common citrus moulds, Penicillium italicum and P. digitatum, responsible for the postharvest diseases of citrus fruits. Fermentation of P. italicum on limonene yielded cis- and frans-carveol (93) (26%) as main products, together with cis- and from-p-mentha-2,8-dien-l-ol (110) (18%), (+)-carvone (94) (6%), p-mentha-1,8-dien-4-ol (111) (4%), perillyl alcohol (100) (3%), p-menth-8-ene-1,2-diol (98) (3%), Fig. (17). Conversion by P. digitatum yielded the same products in lower yields. The two alcohols />-mentha-2,8-dien-1 -ol (110) and p-mentha-1,8-dien-4-ol (111) were not described in the transformation studies where soil Pseudomonads were used [69]. 

This method is of value when the alcohol is readily available from natural sources, or when it can be prepared, for example, by the reaction of an alkenyl-organometallic reagent with an aldehyde. An example of the former is the oxidation of the terpenoid alcohol carveol to carvone (Expt 5.88) using pyridinium chlorochromate-on-alumina reagent. 

Ce4+ is easily exchanged on resins such as Nation. Ce-Nafion catalyzed the oxidation of carveol to carvone with t-BuOOH as the oxidant no data characterizing leaching were provided (59). CeC>2 on AI2O3 was used as a solid catalyst for the cooxidation of cyclohexane and cyclohexanone. Products are dibasic acids and e-caprolactone. It was claimed that in water-free reaction conditions, Ce is not eluted from the solid (342). 

Derivatives of Menthene.— The most important alcohols and ketones derived from the menthene unsaturated group of terpenes are terpineol, di-hydro carveol, di-hydro carvone and pulegone. The first one, the alcohol terpineol, occurs in its dextro form in cardamon oil and marjoram oil, in its leoo form in neroU oil and in its inactive form in cajeput oil. The constitution is proven by Perkin s synthesis from As-tetra-hydro para-toluic acid by means of the Grignard reaction. 

Alkylation of isovaleramide with 1,3-dichlorobut-2-ene yields (139) after methyl-ation acid-catalysed hydrolysis and internal aldol condensation gives ( )-piperitone. The value of piperitenone and isopiperitenone formation, probably via electrocyclic reaction of the pyrolytic acetic acid-elimination product from A - and A -isomers of (49), cannot be assessed in the absence of reaction yields. (S)-(-)-Pulegone is obtained in good yield from (- )-citronellol by oxidation with pyridinium chlorochromate followed by double-bond isomerization. Low-temperature reduction of ( —)-carvone to ( —)-cz5-carveol (140) and... 

Monoterpenols were esterified by lipases from various micro-organisms (especially Aspergillus spp.),931 and ( )-carvyl acetates were hydrolysed by other species to give chiral carveols together with (unreacted) acetates of the enantiomer.932 The metabolic pathways for the conversions of (—)-carvone into (—)-... 

Carveol (5) is one of the minor components responsible for the odour of spearmint, and is easily prepared by reduction of carvone. Isopulegol (6) is prepared from citronellal, as discussed in the section on menthol below, and is a precursor to other materials in the group. The phenols carvacrol (7) and thymol (8) are important in some herbal odour types, but the major use for thymol is as a precursor for menthol q.v. Piperitone (9) and pulegone (10) are strong minty odorants, the latter being the major component of pennyroyal oil. 1,8-Cineole (11) is the major component of such eucalyptus oils as Eucalyptus globulus. These oils are inexpensive and so there is no need to prepare cineole synthetically. Menthofuran (12) is an important minor component of mint oils and can be prepared from pulegone. 

The oxidation of limonene (111) by selenium dioxide has been studied in three laboratories and, using hydroxylated solvents, the major product is mentha-1,8-dien-4-ol (112), in agreement with the results from the selenium dioxide oxidation of carvone (117) where the main product is also the 4-hydroxy-compound (118), also with loss of chirality at C-4. The mechanism giving rise to the secondary chiral products trons-carveol (113) and mentha-l,8-dien-10-ol... 

The use of a two-liquid phase system consisting of a 1 1 mixture of phosphate buffer and dodecane resulted in an increase of the initial (-)-trans-carveol conversion rate by 70% (to 26 nmol per minute and per mg protein). The production was increased from 4.3 to 208 pmol (-)-carvone formed per mg protein as compared to the aqueous system. A simple downstream process consisting of phase separation, methanol extraction, evaporation, and separation of (-)-cis-carveol and (-)-carvone over a silica gel column, was developed. 

An alternative process for the production of (-)-carvone has recently been elaborated. Starting from (-i-)-limonene 1,2-epoxide, a regioselective rearrangement of the epoxide leads to (-)-carveol (trans- -.[2102-58-1] cis- -.[2102-59-2]). The reaction is effected by the use of a catalyst consisting of a combination of metal salts and phenolic compounds. 

The aldehyde has been prepared [165] from (-)-carvone, which was epoxydized and transformed into (+)- ram,-carveol. Orthoacetate Claisen rearrangement and saponification afforded the corresponding y,5-... 

Two examples of the use of PCC in these oxidations come from Vogel. Hexanol is oxidized to hexanal in dichloromethane solution and commercial carveol (an impure natural product) to pure carvone with PCC supported on alumina in hexane solution. In both cases the pure aldehyde or ketone was isolated by distillation. 

Dill weed oil is dominated by a-phellandrene, limonene, and carvone. Dill ether and the absence of dill apiol are further criteria for that oil. Dill seed oil contains mainly carvone and dihydro-carvone. Adulteration is done using phellandrenes, distilled limonene coming from orange terpenes, synthetic carvone, and dihydrocarvone. Detection is done by 2D enantiomeric separation. Lawrence (1996) reports the following ratios for dill seed oil (+)-limonene 98.4% (-)-limonene 1.6% (+)-carvone 98.7% (-)-carvone 1.3% (+)-trans-carveol 33.3% (-)-trans-carveol 66.7% and (+)-cti-carveol 100% (-)-cA-carveol 0%. The authors own ndings from biocultivated oil was (+)-carvone 98.4% (-)-carvone 1.6% (5)-(-)-a-pinene 4.0% (R)-(+)-a-pinene 96.0% (+)-limonene 95.4% (-)-limonene 4.6% (5)-(-)-p-phellandrene 0% (5)-(+) p-phellandrene 100% and (R)-(-)-a-phellandrene 100% (R)-(+)-a-phellandrene 0%. 

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