Trans-carveol

Microalgae were used for oxidation and hydroxylation of organic compounds (Fig. 3). For example, hydroxylation of (5 )-limonene affords a mixture of cis and trans carveols. " By hydroxylation and oxidation using Chlorella, " ... 

An interesting example, although it cannot be described as functional interconversion but rather as isomerisation, was reported by Motherwell and collaborators in 2004 [58]. In this case a polymer was imprinted with a /ram-carvyl amine (97), which was used as TSA, for the isomerisation of a-pinene oxide (98) to trans-carveol (99) that was obtained with 45% yield. 

Alpha-Pinene oxide 9 (Eq. 15.2.5) is known as a reactive molecule which rearranges easily under the influence of an acid catalyst (6, 7). Thereby many products can be formed. For example compounds such as the isomeric campholenic aldehyde 11, trans-carveol 12, trans-sobrerol 13, p-cymene 14 or isopinocamphone 15 are observed as main by-products. At temperatures higher than 200°C more than 200 products can be formed. The industrially most desired compound among these is campholenic aldehyde 10. It is the key molecule for the synthesis of various highly intense sandalwood-like fragrance chemicals (7, 8). 

Other useful p-menthane syntheses of no great novelty are of cis- and trans-piperitol from 2a,3o -epoxycarane (silica-catalysed rearrangement to ds-p-menth-2-en-l,8-diol is also reported), of ( )-dihydrocarvone, isopulegone, and p-menthofuran via /S-keto-sulphoxides, of p-mentha-l,4(8)-diene via a bromination-dehydrobromination sequence, and of trans-carveol by benzoyl peroxide-CuCl oxidation of a-pinene. Further details for the conversion of (-)-(142) into (+)-(142), via its epoxide, are reported (Vol. 5, p. 25 cf. Vol. 3, p. 44). " ... 

As a test reaction a mixture of cis- and trans-carveol was oxidized with TBHP. Analogous to what has previously been observed for compounds like geraniol and linalool, epoxidation was fast and selective (reaction 8). Trans-carveol was converted only to the corresponding epoxide, whereas cis-carveol gave a mixture of cis-epoxide and carvone. 

Table 4. Oxidation of cis- and trans-carveol, catalyzed by vanadium ...

The most important by-products observed are with 6-7 % selectivity the isomeric campholenic aldehyde 3 followed by 2-3 % trans-carveol 4 (Fig. 3). 

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. 

In another study, Rhodococcus globerulus PWD8 was found to oxidize D-limonene regio- and enantioselectively via (-t-)-trans-carveol to (+)-carvone [192l... 

Ring-opening of -pinene with iodine," and of a-pinene with a zinc-copper couple have been mentioned addition of acrolein and methyl acrylate to -pinene may also result in some ring-opened products,and so do the reactions with iodine azide, aldehydes in the presence of light, and ketones in the presence of t-butyl peroxide. Of particular interest in this respect is a paper by Julia et al., who describe the production of cis- and trans-carveols (118) from a-pinene, and perilla alcohol (388) from -pinene with retention of configuration, using benzoyl peroxide in the presence of cupric salts. ... 

Malvaceae limonene, trans-carveol, and y-eudesmol A. retroflexus and L. multflorum, at hi er concentration effective against lettuce, bentgrass, and against one cyanobacterium ... 

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%. 

On the other hand, the high enantioselectivity for 81a was observed in the biotransformation of racemic (+)-tra i-carveol (81a) and -)-trans-carveol (81a ) by Chlorella sorokiniana SAG to give (-) -carvone (93 ). 

Pseudomonas PX 1 biotransformed (+)-a-pinene (4) to give (+)-cA-thujone (29) and +)-trans-carveol (81a) as major compounds. Compounds 81a, 171, 173, and 178 have been identi ed as fermentation products (Gibbon and Pirt, 1971 Gibbon et al., 1972) (Figure 19.150). 

The reference standards of different monoterpenes, sesquiterpenes, and alkanes were obtained from Aldrich Chemical Co., Inc. (Milwaukee, WI, USA), Fluka Chemical Corporation (New York, NY, USA), Roth Co. Chemische Fabrik (Karlsruhe, Germany), Sigma Chemical Co. (St. Louis, MO, USA) and Varian Associated (Houston, TX, USA). These reference standards include tricyclene, a-pinene, sabinene, a-phellandrene, 1-decene, limonene, fenchone, a-terpineol, a-terpinolene, c/s-verbenol, cis- and trans-carveol, cA-dihydrocarveol, a-longipinene, a-cedrene, (-)-isolongifolol, a-humulene, valencene, cuparene, myristyl alcohol, citronellyl acetate, neryl acetate, geranyl acetate, camphene, alloaromadendrene, -eicosane, and n-heneicosane. Solutions were prepared in methanol at concentrations of 10 mg/mL. For GC/MS analysis each standard solution was diluted by mixing 0.1 mL of the standard solution with 0.9 mL of methanol. 

Streptomyces, A-5-1 isolated from soil converted (-)-carvone (93 ) to 101a -102d and -)-trans-carveol (81a ), whereas Nocardia, 1-3-11 converted (-)-carvone (93 ) to (-)-d5 -carveol (81b ) together with 101a -81a (Noma, 1980). In case of Nocardia, the reaction between 93 and 81a was reversible and the direction from 81a to 93 is predominantly (Noma, 1979a, 1979b 1980) (Figure 14.111). 

Figure 22 Direct distillation of beverages by means of the SAFE technique (30 m X 0.25 mm I.D. DB-WAX 0.25 (im df 60°C-3°C/min — 230°C). Key to components identified in soft drink 1, limonene 2, y-terpinene 3, a-terpinolene 4, nonanal 5, hnalool 6, fenchol 7, l-terpinen-4-ol 8, a-terpineol 9, cinnamaldehyde 10, myristicin. Key to components identified in grapefruit juice 1, limonene 2, cis-linalool oxide (f) 3, trans-linalool oxide (f) 4, P-caryophyllene 5, a-terpineol 6, trans-carveol 7, dihydronootka-tone 8, nootkatone.

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