Borneol, from camphor

The most straightforward method involves the conversion of pinene [l] into pinene hydrochloride [2], bornylchloride [3] and hence into borneol [6] (or iso-borneol) from which camphor [7] is obtained by oxidation. Also bornylchloride [3] is converted to isobro-nylacetate [5] upon heating with sodium acetate and glacial acetic acid. Alternatively, c-amphene [U] is oxidatively hydrated to camphor [7]-... 

An efficient route to 7-oxocamphene involved as its key step the solvolytic rearrangement of 3,3-ethylenedioxyisobomyl tosylate (derived from camphor-quinone).621 Brief (3 min 0 °C) treatment (PCl5-CaC03) of borneol gave excellent yields of camphene hydrochloride longer reaction times gave bornyl chlorides.522... 

Bomeol, isobomeol, and camphor are the most important members of the bomane (camphane) family of bicyclic monoterpenes. The labeling pattern of borneol and camphor derived from exogenous [2- C]mevalonate and [2- K jgeraniol in intact tissue is consistent with Ruzicka s hypothesis (Fig. 5) (Banthorpe and Baxendale, 1970 Battersby et al., 1972). Soluble enzyme preparations from sage leaves convert [1- H]NPP to (-t-)-[3- H]bomeol in the presence of Mg and, in the presence of NAD, dehydrogenate the bomeol to (-t-)-[3- H]camphor (Croteau and Karp, 1976b). [1- H]GPP was a less efficient precursor of borneol and camphor in this crude preparation. The epi-... 

The following well-known monoterpenoids have been described from lichens, but without identification of their optical rotation borneol, camphene, camphor, 1,8-cineol, p-cymene, fenchol, limonene, linalool, a-pinene, (3-pinene, terpinen-4-ol, a-terpineol, a-thujone, (3-thujone [all from Evernia prunastri [319)], and carvone [from Cetraria islandica ((555)]. 

Present in citronella and valerian oils, tur penline, ginger, rosemary and spike oils. It is produced artificially by the elimination of hydrogen chloride from bornyl chloride (artifi cial camphor) or from isobornyl chloride, by the dehydrogenation of borneol and isobor-neol and by the action of elhanoic anhydride on bornylamine. Chiral. 

Camphor, Cj HjgO, occurs in the wood of the camphor tree Laurus camphora) as dextro-camphor. This is the ordinary camphor of commerce, known as Japan camphor, whilst the less common laevo-camphor is found in the oil of Matricaria parthenium. Camphor can also be obtained by the oxidation of borneol or isoborneol with nitric acid. Camphor may be prepared from turpentine in numerous ways, and there are many patents existing for its artificial preparation. Artificial camphor, however, does not appear to be able to compete commercially with the natural product. Amongst the methods may be enumerated the following —... 

Esters of bomeol are obtained by the action of dry oxalic acid on turpentine under suitable conditions. From these, borneol is obtained by saponification and is oxidised to camphor. Some other acids produce a similar result, as, for example, salicylic and chlorobenzoic acids. 

Because both enantiomers, (+) and (-)-camphoric add, are available by oxidation either from natural (+)-D-camphor or from natural (-)-L-borneol, both enantiomers of camphanoyl chloride can be prepared conveniently.3 5 The corresponding enantiomers of camphanic acid were described for the first time by Wreden6and Aschan.7 The three-step procedure, described above is an adaptation of procedures described by Aschan,8 Zelinsky et al.,9 Meyer et al.,10 and Gerlach.3... 

Bomeol occurs abundantly in nature as a single enantiomer or, less frequently, as the racemate. (—)-Borneol [464-45-9] occurs particularly in oils from Pinaceae species and in citronella oil. (+)-Bomeol [464-43-7] is found, for example, in camphor oil (Hon-Sho oil), in rosemary, lavender, and olibanum oils. 

Tishchenko (79), using a modified form of Raney nickel, obtained a 95.7 % yield of camphor from the dehydrogenation of borneol. Rutovskii, (80) received a 93.5% yield of camphor with Raney alloy. Reeves and Adkins (81), studying the dehydrogenation of primary alcohols, removed the hydrogen with ethylene. It was found that, though Raney nickel could be used for a catalyst for the reaction, the yields were low and, in general, the Raney nickel was inferior to a catalyst composed of copper, zinc, nickel, and barium chromite. 

Borneol, camphene, and a-pinene are made in nature from geranyl pyrophosphate. The biosynthesis of a-pinene and the related camphor is described in the chapter. In the laboratory bornyl chloride and camphene can be made from a-pinene by the reactions described below. Give mechanisms for these reactions and say whether you consider them to be biomimetic. 

Both an aqueous phase and an oily phase (including waxes and essential oils) were extracted from the herbs. These were collected separately as described in the next section. The essential oils in the oily extract were camphor, verbenone, P-myrcene, 1,8 cineole and limonene for Rosemary and thymol, geraniol and geranyl acetate,carvocrol and borneol for Thyme. 

Camphene is a solid terpene. The dextro variety d-camphene is found in camphor, ginger and spike oils, and the levo variety, 1-camphene is in citrondla and valerian oil and in French and American turpentine. Bornylene does not occur in nature but has been prepared from the alcohol corresponding to it known as Borneol or Borneo camphor. This, as previously stated, may be prepared from pinene so that Bornylene itself may be made from pinene. Fenchene, also, is not found in nature but is obtained by reduction of fenchone a terpene ketone found in fennel oil and in Thuja oil. 

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