Monoterpenoids bicyclic

Another bicyclic monoterpenoid derivative of use in perfumery is nopyl acetate, which has a sweet woody/fruity odour. Prins reaction of 

Bicyclo[3,l,0]hexanes.-Hach has concluded his efforts to provide preparative-scale syntheses of pure (+)-thuj-3-one (30), and (-)-isothuj-3-one, and the four derived thujanols, viz. (+)-thujan-3-ol, (-)-isothujan-3-ol, (+)-neothujan-3-ol (31), and (-)-neoisothujan-3-ol (for earlier related work see Vol. 2, pp. 30, 37, 38 Vol, 4, p. 42 Vol. 7, p. 36). ° A conformational study on these four thujanols indicates that they have a slightly developed boat-like conformation, whereas the five-membered ring in (+)-thuj-3-one (30) and (-)-isothuj-3-one is flat, according 

The nomenclature used by Whittaker (Vol. 5, p. 30) has already been noted in addition, the formula given for (-)-thujan-3-ol is actually that of (+)-thujan-3- 

Further confusion in this field results from Banthorpe using the name (+)-isothujanol for the (+)-neoisothujanol structure Banthorpe uses the same nomenclature as Whittaker. 

Bicyclo[2,2,l]heptanes.—Vulgarole (202 R=Ac) has been isolated from Artemisia vulgaris and Ferula dshizakensis has yielded a new borneol ester, isotschimgin (cf. Vol. 3, p. 58).  

X-Ray diffraction studies of ( )-carbocamphenilone, of (-)-camphene-8-carboxylic acid, and of a number of Money s brominated camphor derivatives (Vol. 6, p. 39 Vol. 7, p. 40) have been published they include 8-bromo-camphor, l,7-dibromo-3,3,4-trimethylnorbornan-2-one, l,7-dibromo-4- 

Bicyclo[3,l,0]hexanes.—Sabinene is the starting material for a synthesis of nootkatone (see Chapter 2, p. 109). It is first converted to sabinaketone (193), which is methylated to the isomer (194) of thujono. Doering has given a very 

Reagents i, HOCH2CH2OH-H ii, Na-MeOD iii, H,0 iv, TsNHNHj v, BuLi vi, A vii, HC=C—COjEt viii, KOH-HjO ix, copper chromite-quinoline. 

The conversion of pinene to camphene (and tricyclene) is a large-scale commercial process. A recent series of papers describes a three-phase system comprising a vertical column in which a liquid suspension of a titanium catalyst in camphene flows downwards, and pinene vapour passes upwards a mathematical 

Reagents i, HBr ii, AgOAc-HOAc iii, LiAlH iv, MeCOjH v, BF,--Et20 vi, SOClj n / vii, EtO viii, Arndt-Eislert procedure. 

Reagents i, HCO2H ii, PhSNa iii, esterify iv, LiAlH4 v, Ni-Hj vi, Brj-CHjClj on sodium salt. 

Bicyclo[2,2,l]heptanes.—Reviews of interest in this section include Brown s on non-classical carbonium ions, Sorensen s on monoterpenoid rearrangements in superacids,and a discussion by Yates of the photochemical ring expansion of cyclic ketones, with particular emphasis on his own work.  

An extensive examination of the minor components of East Indian sandalwood oil has revealed as one component (177), ° which is also synthesized from teresantalic acid by oxidative decarboxylation and cyclopropylmethylhomoallylic rearrangement. 

Electron-impact mass spectral data have been recorded for the trifluoromethane-sulphonates (178 X = 0S02CF3, Y = H) and (178 X = H, Y = OSO2CF3). An Y-ray crystal structure determination of a minor product from the conversion of 3-bromocamphor into (-l-)-9-bromocamphor confirms the structure (179). The 

Catalan and J. A. Retamar, 6th International Congress on Essential Oils [Papers] , Allured Publ. Corp., Oak Park, Illinois, 1974, p. 138 (Chem. Abs., 1976,84,105 789) cf. O. Wallach, Annalen, 1902, 323, 335. 

Deinole, C. Demole, and P. Enggist, Helv. Chim. Acta, 1976, 59, 737. 

Bicyclo[3,2,0]heptanes.—It might have been thought that filifolone (207) could be prepared by cycloaddition of dimethylketen to methylcyclopentadiene (205), but it has been shown that this reaction gives mainly two isomers (206a) and (206b), with small amounts of unidentified byproducts. For the conversion of the pinene skeleton to filifolone, see below. 

Bicyclo[3,l 0]hexanes.— The stereochemistry of the thujane derivatives is still giving rise to discussion and a revised nomenclature has been proposed.  

Conversion of the readily available thujone (211) to 3-thujene (212) has been effected in two laboratories. Thermolysis of the sodium salt of thujone p-toluene-sulphonylhydrazone leads to a 1 1 mixture of the more accessible 2-thujene (210) and 3-thujene (212)/ ° Baldwin and Krauss have raised the yield by treating the same p-toluenesulphonylhydrazone with sodium in acetamide solution. In this reaction 97% of hydrocarbons was obtained, 80% of which was 3-thujene and 20% was y-terpinene (213). The latter method has the advantage of not producing 2-thujene, which is extremely difficult to separate from 3-thujene. 

Norin and L. R. Smedman, Int. Symposium on Synth. Methods and Rearrangements in Alicyclic Chemistry, Oxford, July, 1969, Abstracts p. 21. 

The reaction of umbellulone (215) with JV-bromosuccinimide has been examined. Umbellulone is a hindered ketone, and Wheeler and Chung have shown that while lithium aluminium hydride in ether yields the expected mixture of the two umbellulols (216) and (217), a more bulky nucleophile like lithium tri-t-butoxyaluminium hydride leads almost exclusively to reduction of the double bond to give (218).  

---

Note Valerian consists of the dried rhizome and roots of Valeriana officinalis Linne (Fam. Valerianaceae). It has been employed as an antianxiety agent and sleep aid for more than 1000 years. The drug contains from 0.3 to 0.7% of an unpleasant-smelling volatile oil containing bornyl acetate and the sesquiterpenoids, valerenic acid, and acetoxyvalerenolic acid. Also present is a mixture of lipophilic iridoid principles known as valepotriates. These bicyclic monoterpenoids are quite unstable and occur only in the fresh plant or in material dried at temperatures under 40°C. Although the specific active principals of valerian have not been determined, it is possible that a combination of the sesquiterpenoids and the valepotriates may be involved. The drug may be administered as a tea prepared from 2 to 3 g of the dried herb or equivalent amounts of a tincture or extract may be employed. 

Monoterpenoids are responsible for fragrances and flavors of many plants and thus their products are used in perfumery and as spices. To date over 1,500 monoterpenoids are known, and these constitute acyclic, monocyclic, and bicyclic monoterpenoids (32), which occur in nature as hydrocarbons, alcohols, aldehydes, and carboxylic acids and their esters. Several acyclic monoterpenoid hydrocarbons are known, and these include trienes such as 3-myrcene (Cl), a-myrcene (C2), (Z)-a-ocimene (C3), ( )-a-ocimene (C4), (Z)-3-ocimene (C5), and ( )-P-ocimene (C6). 3-Myrcene and 3-ocimene are constituents of basil (Oci-mum basilicum, Labiatae) and bay (Pimenta acris, Myrtaceae), pettitgrain (Citrus vulgaris, Rutaceae) leaves, strobiles of hops (Humulus lupulus, Cannabaceae), and several other essential oils. Unsaturated acyclic monoterpene alcohol constituents of plants and their derived aldehydes play a signihcant role in the perfume industry. Some common acyclic monoterpene alcohols and aldehydes include geraniol (C7), linalool (C8) (a... 

Additional chemical diversity of monoterpenes is apparent from the natural occurrence of their bicyclic analogs that bear cyclopropane (carane and thujane types), cyclobutane (pinane type), and cyclopentane (camphene/bornane, isoeamphane and fenchone types) rings (Figs. 6 and 7). The carane type of bicyclic monoterpenoids in plants is represented by (+)-3-carene... 

Pinane-type bicyclic monoterpenoids (Fig. 6) occur in the wood of several species of Pinus. The most abundant are a- and p-pinenes (F7 and F8, respectively). Ally lie hydrox-ylation products of pinenes, (+)-verbenol (F9), (+)-myrtenol (FIO), and (—)-pinocarveol (Fll) also occur in nature together with their products of oxidation (-f-)-verbenone (F12), (-h)-myrtenal (F13), and (-)-pinocarvone (F14). (-h)-Verbenol is a constituent of the oil of turpentine. Its regioisomers, (-h)-myrtenol and (—)-pinocarveol, occur in oils of orange Citrus sinensis, Rutaceae) and eucalyptus Eucalyptus globulus, Myrtaceae), respectively. 

Cyclopentane bicyclic monoterpenoids that occur in the plant kingdom belong to three major skeletal types camphane, iso-camphane, and fenchane (Fig. 7). Camphane-type terpenoid alcohols, (+)-bomeol (Gl) and (—)-isobomeol (G2), have been isolated from Cinnamomum camphora (Lauraceae) and Achillea filipendulina (Asteraceae). A ketone derived from these, (-h)-camphor (G3), is found in the camphor tree Cinnamomum camphora) and in the leaves of rosemary Rosmarinus officinalis) and sage Salvia officinalis, Labiatae). Camphene (G4) and its enantiomer with the isocamphane carbon skeleton are known to occur in the oils of citronella and turpentine. Fenchane-type bicyclic cyclopentane monoterpenoids are commonly found in plants as their ketone derivatives. (—)-Fenchone (G5) occurs in the tree of life Thuja occidentalis, Cupres-saceae). Its enantiomer, (+)-fenchone (G6), has been isolated from the oil of fennel Foeniculum vulgare, Umbelliferae). 

Camphor and borneol are widespread bicyclic monoterpenoids in plants. 

Two useful supplementary volumes " " update the corresponding chapters in the second edition of Rodd on acyclic and monocyclic monoterpenoids/ on bicyclic monoterpenoids,and on the biogenesis of mevalonate, hemiterpenoids, and monoterpenoids.A useful textbook on natural plant constituents includes some biochemistry and chemistry of monoterpenoids. ... 

Mass spectral papers include another compilation of monoterpenoid alcohol spectra, a comparison of fragmentation patterns for camphor and menthone with their oxime, semicarbazone, and nitrophenylhydrazone derivatives, and a comparison of collisional activation mass spectra of ten related acyclic, monocyclic, and bicyclic monoterpenoid hydrocarbons together with derived 7119 ions. ... 

The commonest bicyclic monoterpenoid skeleta are shown in Figure 5.1. The bicyclic monoterpenoids are all formed from geranyl pyrophosphate... 

Some important bicyclic monoterpenoids are shown in Figure 5.2. Camphor occurs very widely in nature. The richest source is the oil distilled from the wood of the camphor tree (Cinnamomum camphor a). This wood has a long history of use for furniture in China. Linen stored in camphorwood chests is free from attack by insects such as moths owing to the insect repellent properties of camphor. It is also found in a wide range of flowers, such as lavender, and herbs, such as sage and rosemary. Isobornyl acetate occurs in herbs such as sage,... 

We saw how Jra/is-annular reactions are common in carbocation chemistry. The close proximity of atoms in polycyclic systems means that, not only carbocation reactions, but also carbanion and free radical are prone to take place across the ring system. Figure 5.41 shows an anionic reaction in a bicyclic monoterpenoid. 

---