A Cedrene

Acetyl cedrene (95) is obtained by the acetylation of the hydrocarbon fraction, a-cedrene [469-61-4] (91). The product has a woody, warm-ambergris, and musk odor, and many types of products are available (189). 

From the intermediate A, cedrene was also made by an alternative route ... 

When cedrene was oxidised with permanganate, there were chiefly formed products of an acid nature, from which a cedrene keto acid, CjjHj Oa, was isolated, which boiled at 215° to 222° (11 mm. press.). Its semicarbazone melts at 245° and its oxime at 60°. 

The second chemotype (their Type 1) had, in addition to the Type 0 array, substantial amounts of a-longipinene [297] and an unidentified sesquiterpene alcohol. The third chemotype (their Type 2) was distinguished by the presence of, among other compounds, cedrene isomers, [a-cedrene is shown as 298], and large amounts of the isomeric sesquiterpene alcohols a-acorenol [294] and its P-isomer [295]. The acora-diene isomers [295 and 296] were also identified. Some geographic patterning was observed in the Type 0 chemotype when the data were subjected to numerical analysis a trend in the reduction of caryophyllene content was revealed in a west to east direction. The data sets for Types 1 and 2 were too small to allow for similar analysis. 

In a similar way, a-cedrene has been synthesized by the same group [35]. Moreover, these authors have also developed a further access to modhephene (3-70) using a free-radical 6-mdo-/5 - exo-do rn i rio cyclization of a dieneyne [36]. 

The uniqueness of the intramolecular 1,3-photocycloaddition of arenes to olefins with the developement of three new rings and up to six stereocentres has been efficiently demonstrated in the synthesis of (+)-a-cedrene from the... 

While the pheromones of Tenebrio and Tribolium originate from a mixed biosynthesis, those produced by males of the broad horned flour beetle, Gnatho-cerus cornutus, represent true terpenes. Initially, the configuration of this new pheromone had been erroneously proposed to be (IR,4R,5S) a-acoradiene [325] however, independent syntheses of pure stereoisomers [326,327] proved the correct structure to show (lS,4A,5A)-configuration 165. The scope of the synthesis is shown by Mori (see chapter by Mori in volume 1 and [15]). A minor component of the G. cornutus was reported to be a-cedren-14-al 166 [328]. 

C17H26O, Mr 246.39, is a long-lasting wood fragrance which is prepared by acetylation of cedarwood oil fractions that contain sesquiterpene hydrocarbons, mainly a-cedrene and thujopsene. Acetylation is carried out in the presence of an acidic... 

Cedarwood Cupressus funebris Endl. Cedrol (10-16), a-cedrene... 

These intramolecular meta-addition processes were utilized in the key steps for the total synthesis of a-cedrene [245], isocomene [246], hirsutene [247], coriolin [248], silphinene [249], rudmollin [250], laurenene [251], and fenestranes [252-254], which were synthesized by Wender s and Keese s groups (Scheme 58). 

Chappell, D. and Russell, A.T. (2006) From a-cedrene to crinipellin B and onward 25 years of the alkene-arene meta-photocycloaddition reaction in natural product synthesis. Organic tg Biomolecular Chemistry, 4 (24), 4409-4430. 

Patra, D. and Ghosh, S. (1995) Photocycloaddition-cyclobutane rearrangement to spiro cyclopentanones application in a formal synthesis of ( )-a-cedrene. Journal of the Chemical Society, Perkin Transactions 1, 2635-2641. 

Wender PA, Howbert JJ, Dore TM. The total synthesis of (+/—)-a-cedrene. In Mattay J, Griesbeck AG, eds. Photochemical Key Steps in Organic Synthesis. Weinheim VCH, 1994 181-185. 

Fig. 5-3. Examples of mono- and sesquiterpenes and their derivatives in softwood. 1, a-Pinene 2, /3-pinene 3, 3-carene 4, camphene 5, borneol (R = H), bornyl acetate (R = COCH3) 6, limonene 7, a-terpineol 8, dipentene 9, a-muurolene 10, 8-cadinene 11, a-cadinol 12, a-cedrene 13, longifolene 14, juniperol.

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