Sabinene hydrate

Aerial parts of N. sintenisii yielded 0.3% of a clear yellowish oil. Forty constituents (96.5% of the total oil) were identified. The main components were 4aP,7a,7aP-nepetalactone (23.4%), elemol (16.1%), E- -farnesene (9.5%), 1,8-cineole (8.2%), cw-sabinene hydrate (6.5%), P-bisabolene (4.2%), germacrene-D (3.5%), P-sesquiphellandrene (2.8%), P-bourbonene (1.5%) and a-epi-cadinol (1.3%). According to available data, Nepeta species can be divided into two groups of nepetalactone-containing and nepetalactone-free species. The results of this study indicate that the compositions of volatile oil of N. sintenisii are similar to the other Nepeta genus and this plant could be classified in the group which 4aP,7a,7aP-nepetalactone is the major component of their oils. 

The first natural product synthesis that utilized the Stetter reaction was reported by Stetter and Kuhhnann in 1975 as an approach to aT-jasmone and dihydrojas-mone (Scheme 21) [93]. Thiazolium pre-catalyst 74 was effective in catalyti-cally generating the acyl anion equivalent with aldehydes 144 and 145, then adding to 3-buten-2-one 146 in good yield. Cyclization followed by dehydration gives cii-jasmone and dihydrojasmone in 62 and 69% yield, respectively, over two steps. Similarly, Galopin coupled 3-buten-2-one and isovaleraldehyde in the synthesis of ( )-rran5-sabinene hydrate [94]. 

The use of enantiomers as additional markers for taxonomic characterization of aromatic plants may be very helpful. The differences in the enantiomeric distribution of trans- and cis- sabinene hydrates in two Origanum species enable the species to be distinguished in spite of their similar essential oil compositions. A further study on the natural variation of the enantiomeric composition within a wild population may be carried out in order to examine the stability in a taxon (including the possible presence of chemotypes). The enantiomeric ratio of essential oil components is a reliable parameter for assessing quality because it may be indicative of adulteration, contamination, aging, shelf life, technological process and the botanical source of a specific chiral compound. ... 

The bicyclic monoterpenes cis-sabinene hydrate and cit-sabinene hydrate acetate are known as the major and original flavor compounds of marjoram Origanum majorand) Relatively large quantities of cis- and trans-sabinene hydrate were detected in the genus Origanum m-Sabinene hydrate acetate was found in relatively large amounts in solvent and CO2 extracts of O. and as a minor component in hydro-... 

Larkov O, Dunkelblum E, Zada A, Lewinsohn E, Freiman L, Dudai N, Ravid U, Enantiomeric composition of trans- and cis- sabinene hydrate and their acetates in five Origanum spp., Flavour Fragr/22 109—114, 2005. 

Novak J, Bitsch C, Langbehn J, Pank F, Skoula M, Gotsiou Y, Franz CM, Ratios of cis- and tra wr-sabinene hydrate in Origanum majorana L. and Origanum microphyllum (Bentham) Vogel, Biochem Syst Ecol 28 697—704, 2000. 

Novak J, Bitsch C, Pank F, Langbehn J, Franz CM, Distribution of the cis-sabinene hydrate acetate-chemotype in accessions of marjoram Origanum majorana L.), Euphytica 127 69-74, 2002. 

Karasawa D, Shimizu S, Mentha candicans, a new chemical strain of section Spi-catae, containing tntwr-sabinene hydrate as the principal component of essential oil, Agric Biol Chem 42 433 37, 1978. 

The main constituent of the oil is l-terpinen-4-ol (>20%), which with (+)-cw-sabinene hydrate [15537-55-0] (3-18%) is responsible for the characteristic flavor and fragrance of marjoram oil [614-620bj. 

Thujane-type monoterpenes, unusual monoterpenes with a cyclopropane ring in a bicyclo[3.1.0] skeleton, are formed from the terpinen-4-yl cation directly or via the sabinyl cation. Important members include a-thujene 52, sa-binene 53, the cis isomer 54 of sabinene hydrate, sabinol 55, sabinylacetate 56, a-thujone 57, -thujone 58 and isothujanol 59 (Structure 4.13). 

Figure 5.6 Proposed mechanism for the cyclization of geranyl diphosphate to sabinene and sabinene hydrate under catalysis by monoterpene synthases the reaction begins with the hydrolysis of the diphosphate moiety to generate a resonance-stabilized carbocation (1) the carbocation then isomerizes to an intermediate capable of cyclization by return of the diphosphate (2) and rotation around a single bond (3) after a second diphosphate hydrolysis (4) the resulting carbocation undergoes a cyclization (5) a hydride shift (6) and a second cyclization (7) before the reaction terminates by deprotonation (8) or capture of the cation by water (9). Cyclizations, hydride shifts and a variety of other rearrangements of carbocationic intermediates are a characteristic of the mechanisms of terpene synthases. No known terpene synthase actually produces both sabinene and sabinene hydrate these are shown to indicate the possibilities for reaction termination. PP indicates a diphosphate moiety.

The short synthesis of (+)-frans-sabinene hydrate, an important flavor chemical found in a variety of essential oils from mint and herbs, was developed by C.C. Galopin. The key intermediate of the synthetic sequence was 3-isopropyl-2-cyclopentenone. Initially a Nazarov cyclization of a dienone substrate was attempted for the synthesis of this compound, but the cyclization did not take place under a variety of conditions. For this reason, a sequential Stetter reactionlintramolecular aldol condensation approach was successfully implemented. 

Galopin, C. C. A short and efficient synthesis of ( )-trans-sabinene hydrate. Tetrahedron Lett. 2001,42, 5589-5591. 

Composition Main constituents are a- and y-terpinene, terpinene-4-ol, a-terpineol, linalool, linalyl acetate and cis-sabinene hydrate. The latter, along with its transisomer and terpinene-4-ol, is considered as typical aroma carrier of sweet marjoram. The quantitative composition, especially of oils of uncertain botanical origin, varies considerably ]155]. Oils from India contain eugenol, methyl chavicol and geraniol in marked amounts ]156], while these compounds are negligible or absent in European oils. Commercial oils from Turkey contain considerable amounts of carvacrol, some up to 80% [157]. Also the production process can influence the oil composition, e.g. cis-sabinene hydrate is partly converted to terpinene -ol during steam distillation. The genuine plant additionally contains cis-sabinene hydrate acetate, which is almost totally hydrolysed in the steam-distilled oil [158]. 

Composition 30-55% (-)-menthol, 14-32% (-)-menthone, 1.5-10% (-i-)-iso menthone, 2.8-10% menthyl acetate, 3.5-14% 1,8-cineole, 1-9% menthofuran, up to 4% pule-gone [220], as well as 3-octanol, trans-sabinene hydrate, piperitone, viridrflorol, mono- and sesquiterpene hydrocarbons. For further constituents see [221, 222, 223[. On the differentiation between peppermint oils and the detection of dementholised commint oil as a major adulterant see the results of Lawrence et al. [224], The ratio of 1,8-cineole limonene (min. 2) was even implemented in the European Pharmacopoeia. The latter also limits the isopulegol content for Mentha piperita oil to 0.2%. 

Composition 70-80 % (-)-menthol. The commercially available oils are dementholised and again rectified, contain mainly menthol (33 6%), menthone (18-32%), isomenthone (8-14%) and menthyl esters, and are employed for diluting the more expensive piperita oils. The composition of the unrectrfied oil is similar to that of piperita oil, whereas (E)-sabinene hydrate, viridiflorol and menthofuran are only present in traces. Isopulegol occurs up to 3%. 

The new natural product 765 (R = CHO) is reported to occur in juniper,but there is no information about stereochemistry or synthesis. The corresponding acid 765 (R = COOH) was said to occur in carrots. " Diterpene acid esters of sabinene hydrate (766) have been isolated from flowers of Helianthus annulus. 

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