Caryophyllene oxide

The structure of caryophyllene oxide (shown in Section 6.1) is significantly more complicated and is a worthy challenge for the methods we are describing in this chapter. We shall soon see that COSY has its limita- 

FIGURE 6.12. (a) 300-MHz H NMR spectrum and (b) 75-MHz l3C NMR spectrum and DEPT spectra for caryophyllene oxide. 

The exocyclic olefinic methylene protons show obvious COSY correlations to one another. In addition, we note a very weak cross peak between the deshielded olefinic proton and an apparent quartet at 2.60 ppm. This interaction is reminiscent of the long-range allylic 

09 ppm. Since C-6 is a quaternary carbon, the HMBC experiment enables us to see through these normally insulating points in a molecule. Other assignments are left to the reader as an exercise the quaternary carbon at about 143 ppm (C-6) is a good place to start. 

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An illustration of the plethora of reactions that may occur is afforded by the transformation of caryophyllene oxide by Botrytis cinerea. Although most of the reactions were hydrox-ylations or epoxidations, two involved transannular reactions (a) between the C4-epoxide oxygen and Cy and (b) between the C4-epoxide and C13 with formation of a caryolane (Figure 7.47) (Duran et al. 1999). 

FIGURE 7.47 Transformation of caryophyllene oxide by Botrytis cinerea. 

Duran R, E Corrales, R Hemandez-Galan, IG Collado (1999) Biotransformation of caryophyllene oxide by Botrytis cinerea. J Nat Prod 62 41-44. 

Figure 10.4 Temperature profiles for three classes of analytes monoterpenes (limonene) sesquiterpenes [(3 caryophyllene, caryophyllene oxide (caryo. oxide)] and diterpenes [cem brene A, isoincensole acetate (iso. acetate)]. PDMS fibre, sampling time 40 min. Reproduced from S. Hamm, E. Lesellier, J. Bleton, A. Tchapla, J. Chromatogr., A, 1018, 73 83. Copyright 2003 Elsevier Limited...

Sampling time 60 min extraction temperature 80°C. Monoterpenes a-pinene, p-myrcene, a-phellandreneand limonene sesquiterpenes a-cubebene, a-copaene, p-elemene, p-caryophyllene, a-humulene, y-muurolene, p-eudesmene and caryophyllene oxide diterpenes cembrene A and isoincensole acetate. 

The first observation is the similarity between the chemical compositions of both the Boswellia carteri and Boswellia sacra. For these three olibanum samples, a-pinene (2), (3-myrcene (8) and limonene (14) are the predominant monoterpenes. p-Caryophyllene (73) is the major sesquiterpene besides a-copaene (65), a-humulene (also called a-caryophyllene) (78) and caryophyllene oxide (95). The characteristic olibanum compounds isoincensole and isoincensole acetate (128) together with cembrene A (120) are the main diterpenes. 

Boswellia serrata olibanum has a chemical composition close to that of both the B. carteri and of B. sacra, but contains compounds that are absent in those from other Boswellia and could be used as markers methylchavicol (38), p-anisaldehyde (47), methyleugenol (70), isocaryophyllene (82), sesquiterpene 91, elemicin (92) and an unidentified diterpene (124) eluting between cembrene C (123) and verticilla-4(20),7,ll-triene (125). It is devoid of (5-caryophyllene (73), a-humulene (78), caryophyllene oxide (95) and bornyl acetate (50). 

Eight olibanum samples of unknown botanical origin have been analysed [26]. The chemical compositions are summarized in Table 10.3 for three of them. Both the olibanum coming from Somalia and that from a market in Ta izz (Yemen) have been attributed to Boswellia carteri or sacra on the basis of the occurrence of the characteristic diterpenes isoincensole and isoincensole acetate (128) together with diterpene 126. The absence of methylchavicol (38), oxygenated sesquiterpene 91 and diterpene 124 and the presence in relatively large amount of (3-caryophyllene (73), ot-humulene (78) and caryophyllene oxide (95) excluded the hypothesis of a B. serrata sample. 

Resistant hirsutum race stocks Texas No. 254 and 810 also are deficient of bisabolene and B-bisabolol stocks 810, 1055, and 1123 have greatly increased caryophyllene oxide contents and stock 953 has greatly reduced concentrations of caryophyl 1 ene, caryophyl 1 ene oxide, and humulene (Table II). It is tempting to attribute the known increased resistance to insects in the Texas race stocks to the changes in volatile profiles, but this hypothesis remains to be proven. 

Scheme 21 BiBr3-catalyzed reaction of (—)-caryophyllene oxide under Ritter reaction conditions...

By using betulin as substrate, some mechanistic studies were performed and it was demonstrated that these reactions are catalyzed by Brpnsted acid species generated in situ from the hydrolysis of Bi(0Tf)3-.vH20. This process was also applied to other terpenic compounds. The sesquiterpene ( )-caryophyllene oxide originated clov-2-en-9a-ol by a cariophyllene-clovane rearrangement (Scheme 41) whereas 3-oxo- l 8a-olean-28- l 3(3-olide was obtained from oleanonic acid (Scheme 42). With this triterpene derivative, only 28,13(3-lactonization occurred, with inversion of the configuration of the stereocenter at C18 [133],... 

Scheme 41 Bi(0Tf)3-xH20-catalyzed Wagner-Meerwein rearrangement of (—)-caryophyllene oxide...

Cyclic ethers used as fragrances include a number of terpenoid compounds. Some of them, such as 1,4-cineole [470-67-7] and 1,8-cineole, occur in essential oils in significant quantities. Others are only minor components examples are rose oxide, nerol oxide [1786-08-9], and rose furan [15186-51-3], which contribute to the specific fragrance of rose oil. Caryophyllene oxide [1139-30-6], which has a woody,... 

Vitex chinensis Miller V. jeguaod L. Mu Jing (leaf) Essential oils, beta-caryophyllene, caryophyllene oxide.33 Antitussive, antiasthmatic, antibacterial. 

Caryophyllene Caryophyllene oxides Caryophyllene methyl ketone... 

Chapters 3 and 4 (familiarity with which is assumed) provide us with powerful techniques and methods to elucidate the structures of organic compounds especially when combined with information derived from IR and mass spectrometry. These NMR methods are collectively referred to as one-dimensional techniques. To extend our capabilities, we turn once more to NMR. We will use four compounds as examples ipsenol (see Chapter 3), caryophyllene oxide (a sesquiterpene epoxide), lactose (a j3-linked disaccharide), and a small peptide (valine-glycine-serine-glutamate, VGSE). The structures of these compounds are shown in Figure 5.1. 

We did a credible job of interpretation of ipsenol using H NMR in Chapter 3, but we can do a better job using correlation methods, quicker and with less ambiguity. Caryophyllene oxide, lactose, and VGSE are, however, too complex to fully analyze using onedimensional H and 13C NMR alone. Before turning our attention to the description of specific experiments and their interpretation, we will first take a closer look at pulse sequences and Fourier transformation. 

Before undertaking detailed discussions of H— H COSY and the structure of ipsenol, there is one further experimental refinement that decreases the clutter along the diagonal. Although we can interpret this spectrum without this refinement, there are instances (i.e., caryophyllene oxide) when this improvement makes a great deal of difference. 

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