Verbenol Verbenone

The MIL-supported POM eatalysts were eharaeterized by elemental analysis, XRD, N2 adsorption, and FT-IR-speetroseopy, whieh indieated the preservation of both MIL and POM structures after immobilization. The eomposite M-POM/MIL-101 materials demonstrated fairly good catalytie performanee in a-pinene allylie oxidation (81-84 % verbenol/verbenone seleetivity at 15-25 % substrate eonversion) and earyophyllene epoxidation (100 % selectivity at 88 % conversion) with green oxidants - H2O2 (Ti-POM) and O2 (Co-POM) [126]. 

The catalytic properties Co-POM/Si02 were assessed in oxidation of IBA to isobutyric acid [96] and a-pinene to verbenol/verbenone [97] with molecular oxygen as well as in a-pinene/lBA co-oxidation to produce the corresponding epoxide and carboxylic acid [97]. In turn, the catalytic performance of Ti-POM/Si02 was examined in a-pinene oxidation to... 

It is convenient to here mention the hydrocarbon verbenene, C,gH,4, on account of its relationship with pinene. It results from the action of acetic anhydride on verbenol, thei alcohol corresponding with the ketone, verbenone. So produced it is laevo-rotatory. The dextro-rotatory and racemic varieties are also known. The sesquiterpenes have the following characters when regenerated from their respective dibromides —... 

The catalysts Co-CMS5 and C0-CMS6 have also been tested for the air oxidation of a-pinene. In both the cases air oxidation commences quickly with the formation of a-pinene oxide, verbenol and verbenone as the main products along with other rearranged products as observed in the reactions described above. A conversion of 50.6% and 48.0% are observed for Co-CMSS and C0-CMS6 respectively after 24h (Table 6). 

Biotransformation of (+)- and -)-cis/trans- etheno s to (-f)-verbenone has been achieved by a cell-free system of Cannabis sativa Callus.The (—)- and (+)-verbenone (via verbenol) were the starting materials for the first synthesis of the (—)- and (+)- enantiomers of A -tetrahydrocannabinol. 

Also the biotransformation of a-pinene derivatives and other pinane monoterpenoids by Cephalosporium aphidicola has been described [101]. The best conversion was the oxidation of verbenol to verbenone (yield 61%). 

Weber e.t al. utilized dinuclear (i-oxo iron(III) phthalocyanines 18 as catalysts in the aerobic oxidation of a-pinene lg, resulting in the formation of trans-verbenol 2g, verbenone 3g and a-pinene oxide 4g in almost equimolar amounts. Additionally, 3-pinen-2-ol 19 was obtained (Scheme 3.28) [119]. 

Hunt D. W. A. and Borden J. H. (1989a) Conversion of verbenols to verbenone by yeasts isolated from Dendroctonus ponderosae (Coleoptera Scolytidae). J. Chem. Ecol. 16, 1385-1397. 

Leufven A., Bergstrom G. and Falsen E. (1984) Interconversion of verbenols and verbenone by identified yeasts isolated from the spruce bark beetle Ips typographus. J. Chem. Ecol. 10, 1349-1361. 

Both a- and P-pinenes are popular starting materials for the synthesis of other monoterpene chiral synthons such as carvone, terpineol, and camphor (vide infra). Reactions leading to other monoterpenes are briefly summarized in Figure 5.1. Treatment of a-pinene with lead tetraacetate followed by rearrangement gives trans-verbenyl acetate (7), which is hydrolyzed to yield trans-verbenol (8) 8 Subsequent oxidation of 8 gives verbenone (9), which can be reduced to give cw-verbenol... 

The adsorptive separation of pinenes on Zeolites is reported.303 The C-6 and C-7 13C n.m.r. chemical shifts in bicyclo[3,l,l]heptanes support other known conformational evidence and confirm that cls-pinane and ds-myrtanol (209 X = OH) have a bridged-boat conformation, that trans-myrtanol has a bridged-chair conformation, and that trans-2-pinanol and myrtenol (210 X = OH) have Y-shaped conformations verbenone (211 R R2 = O), and trans-verbenol (211 R1 = H, R2 = OH) give anomalous results which may be due to a conjugation effect the bridged-chair... 

The aggregation pheromone of Dendroctonus brevlcomls Leconte consists of a synergistic mixture of exo-brevicomin (IV) produced by females, myrcene (V) from the host tree, and frontalin (VI) produced by males which respond to compounds IV and V. The mixture of all three compounds then attracts males and females (10). Subsequently, verbenone (VII) and trans-verbenol (VIII) are produced and deter further attack (11.). Additionally verbenone deters the response of I. paraconfusus which utilizes the same host tree species in the same area (16,17). Thus the two species may be found colonizing different parts of the same tree. Again, as in the Ips pheromones, chirality plays a role. The naturally occurring enantiomers of exo-brevicomin and frontalin in combination with myrcene elicit a greater response from both male and female D. brevlcomls than do the other enantiomers. 

Examples of the use of chromium(VI) reagents to effect the allylic oxidation of alkenes to give a,3-unsaturated carbonyl compounds are very common in the literature. The reaction was first reported by Treibs and Schmidt for the allylic oxidations of a-pinene to verbenone and verbenol, of dipentene to carvone and caiveol, and of cyclohexene to cyclohexenol and cyclohexenone, using a solution of chromium trioxide in a mixture of acetic anhydride and carbon tetrachloride. However, yields were low and no synthetic use of this observation was made. 

The most abundant bicyclic terpene in nature, x-pinene (14), has been the substrate for several microbiological transformation studies334,335. Aspergillus niger NCIM612, a strain selected from a number of fungal strains isolated from infected bark, exhibits maximum transformation capacity in shake cultures, with deep-tank fermentations being less successful. Transformation products of importance from (-)-x-pinene are 4,6,6-trimethylbicyclo[3.1.1]hept-3-en-2-ol [( + )-rir-verbenol, 15, the major product], trimethylbicyclo[3.1.1]hept-3-en-2-one [(+ )-verbenone, 16] and 5-hydroxy-a,x,4-trimcthyl-3-cyclohexene-l-methanol [(+)-trao.s-sobrerol, 17]33S-337. 

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. 

It is suggested that micro-organisms introduced by Dendroctonus frontalis may be responsible for the conversion of the aggregation pheromone trans-verbenol into verbenone which inhibits further attack by the pine bark beetle (cf. Vol. 6, pp. 13, 179, 180). ... 

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