Sabinene

Figure Bl.16.1. CIDNP spectrum (250 MHz top) observed during irradiation of chloranil with sabinene...

Roth et aJ [10] have used CIDNP to study the structures of vinylcyclopropane radical cations fomied from precursors such as sabinene (1). 

Sabinene and carene are isomeric natural products with the molecular formula CjoHig (a) Ozonolysis of sabinene followed by hydrolysis in the presence of zinc gives compound A What IS the structure of sabinene" What other compound is formed on ozonolysis" (b) Ozonoly SIS of A carene followed by hydrolysis in the presence of zinc gives compound B What is the structure of A carene" ... 

Sabinene is a monoterpene found in the oil of citrus fruits and plants It has been synthe sized from 6 methyl 2 5 heptanedione by the sequence that follows Suggest reagents suitable for carrying out each of the indicated transformations... 

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. 

Mondello et al. (2, 20-23) have used a multidimensional gas chromatographic system based on the use of mechanical valves which were stable at high temperatures developed in their laboratory for the determination of the enantiomeric distribution of monoterpene hydrocarbons (/3-pinene, sabinene and limonene) and monoterpene alcohols (linalol, terpinen-4-ol and a-terpineol) of citrus oils (lemon, mandarin, lime and bergamot). Linalyl acetate was also studied in bergamot oil. The system consisted of two Shimadzu Model 17 gas chromatographs, a six-port two-position valve and a hot transfer line. The system made it possible to carry out fully... 

By systematic fractionation of a large quantity of sabinene obtained from oil of savin, Schimmel Co. separated the crude terpene into the following fractions —... 

By the action of hydrochloric acid gas on sabinene dissolved in acetic acid, terpinene dihydrochloride is produced, melting at 52°. If no trace of moisture is present the monohydrochloride alone is yielded. 

By oxidising sabinene with ice-cold solution of potassium pci-manga-nate, sabinene glycol, C,(,H,g(OH)2, results. This body melts at 54°, and, together with the above-described hydrochloride serves for the characteri-... 

To prepare sabinenic acid for the identification of the terpene, Wallach operates as follows 10 grams of the crude terpene are mixed with the theoretical amount of potassium permanganate in water at ice temperature. The oxide of manganese is filtered off, the liquid rendered acid and extracted with ether, and the ethereal solution shaken with caustic soda solution. The sodium salt is very sparingly soluble, and is precipitated, collected, and decomposed with dilute sulphuric acid and purified by a further solution in ether. It must be well dried in a desiccator before its melting-point is determined. Sabinene has the following constitution —... 

Sabinene appears to be fairly closely related to thujene (tanacetene), since both a-thujene and /3-thujene yield the same body, thujane CjjHjg, as does sabinene when reduced by hydrogen in the presence of platinum black. 

Considerable difference of opinion exists as to the relationships of sabinene to terpinene, and the conversion of sabinene into terpinene hydrochloride is to be explained by a molecular rearrangement, and cannot be said to be evidence of relationship. ... 

By treating sabinene with formic acid at reduced temperatures Semmler has obtained an alcohol of the formula CjpHjgO which has the following characters —... 

The following formula has been suggested for thujene, which is in accord with its obvious relationship with sabinene... 

Wallach has prepared a-phellandrene synthetically from sabinenic acid by oxidising it to sabina ketone with potassium permanganate. This ketone was converted into its semicarbazone, and the latter compound treated with dilute sulphuric acid, when sabina ketone is not regenerated, but an isomer, which was found to be isopropyl-hexenone. By the interaction of this body with methyl-magnesium iodide, loss of water occurs with a simultaneous conversion into a-phellandrene, which appears to be a mixture of the dextro- and laevo- varieties. This syntheticallj prepared a-phellandrene has the following characters —... 

It results from the oxidation of sabinenic acid with peroxide of lead, sabinenic acid itself being an oxidation product of the terpene sabinene. It is a liquid having the following characters —... 

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