Civetone

The telomer obtained from the nitromethane 65 is a good building block for civetonedicarboxylic acid. The nitro group was converted into a ketone, and the terminal alkenes into carboxylic acids. The acyloin condensation of protected dimethyl dvetonedicarboxylate (141) afforded the 17-membered acyloin 142, which was modified to introduce a triple bond 143. Finally, the triple bond was reduced to give civetone (144)[120). 

Many cycHc ketones occur in natural oils. Jasmone [488-10-8] (3-meth5l-2-(2-pentyl)-2-cyclopenten-l-one) (4) is an odoriferous component of the oil obtained from jasmine flowers. /-Menthone [14073-97-3] (5) is the most frequently occurring of four optically active isomers, and is a colorless Hquid with a minty odor obtained from Mentha species of plants. Muscone [541-91-3] (6) and civetone [542-46-1] (7) are expensive animal products. 

The telomer of nitromethane with four moles of butadiene 62 has a chain of 17 carbons, and this compound is a very suitable starting material with right carbon numbers and necessary functionalities for the synthesis of civetone (133), a naturally occurring fragrant compound. The telomer was converted into civetonedicarboxylic acid (132) by the following sequence of reactions ... 

Civetonedicarboxylic acid was then converted into c/s-civetone (133) by acyloin condensation and the following steps (124) ... 

These reactions, which are believed to occur predominantly inter-molecularly, are capable of producing intermediates which hold some potential as precursors for important chemical products. For example, metathesis of olive oil, which consists chiefly of triglycerides of oleic acid, produces the glyceride of 9-octadecene-l,l8-dioic acid from which can be obtained, after saponification, acidification, and low-temperature crystallization, the free acid, which can be transformed by intramolecular condensation to civetone. 

Civet civetone / polyket. Q ° civetone civet cat, Civettictis [= Viverra] civetta (Schreber, 1776), Mamm./fixative in expensive perfumery trtal synthesis... 

Ketones are most widely represented and include cyclopentanone derivatives, such as the jasmin fragrance substances, and cyclic ketones with 15-17-membered carbon rings, such as muscone and civetone, which are constituents of the extremely expensive animal products, musk and civet. Cyclopentadecanone, a natural musk fragrance, and the unsaturated 5-cyclohexadecen-l-one, which has not yet been found in nature, have odor characteristics similar to those of muscone and civetone and are more easily synthesized. They are, therefore, often used as substitutes. 

The animals are kept in cages, and the fresh secretion is taken from the pouches at regular (about one-week) intervals. Civet is almost liquid with a light yellow color. It darkens when exposed to light and takes on a consistency like salve. In dilutions (e.g., as an alcoholic tincture), civet has a pleasant, sweetish odor. A resinoid prepared by extraction with acetone is a dark brown-red mass [257]. Civetone (see p. 88) is the main odoriferous constituent of civet (2.5-3.4%). Civet contains other macrocyclic ketones such as cyclohexa- and cycloheptadecanone and 6-cw-cycloheptadecenone. Traces of indole and skatole contribute to the animal note [258]. 

Macrocyclic ketones. This reagent has been used for cycloolefination of acetylenic dialdehydes (Wittig-Horner reaction) as a route to muscone, exaltone, and civetone. A synthesis of the last ketone (3) is formulated (equation 1). 

The ketones 47-49 can be made in good yield (55-95%) by RCM of the appropriate diallyl compounds using 8 as catalyst234. If the spacing between the two C=C bonds in the reactant is increased to ten bonds, then ADMET polymerization is the preferred reaction at normal concentrations. However, by working at 10-3 M it is possible to favour the RCM of oleon (50), equation 35, to give civetone (51) (musk odour) with a yield of up to 14%235. This method of preparation of 51 has the advantage that the metathesis reaction... 

The complex WOCI4—Cp2TiMe2 was used for the metathesis of ethyl oleate (51) to give diethyl 9-octadecenedioate (52). Civetone (53) was synthesized by the Dieckmann condensation of this diester, followed by decarboxylation [20], Homometathesis of terminal alkenes is useful, because it yields symmetric internal alkenes and ethylene, which can be removed easily. Metathesis of 10-undecenoate (54) proceeds smoothly to give the diester 55 [20],... 

Compounds 136 containing an unsaturated macrocycle were obtained with yields of up to 85% from civetone 135 and isatins 42 [128, 129],... 

Civetone (a perfume ingredient from the civet cat) (heptadec = 17)... 

The preputial (musk) gland of the muskrat contains a number of macrocyclic ketones, such as isomers of civetone (cis-9-cycloheptadecenone), the main odourous component of the secretion of the civet. In the muskrat the main macrocyclic component is the cis-5-isomer of civetone (Figure 9). The glands of both animals also contain a number of other macrocyclic compounds and a variety of fatty acids (24,25,26) which could be precursors of macrocyclic ketones and alcohols as proposed by Stevens in 1945... 

The structural elucidation of civetone and muscone as large-ring ketones by Ruzicka... 

Similarly cyclododecyne (4) was synthesized from 1,2-dichlorocyclododecane (3)-. Civetone (7), a natural perfume of animal origin, w-as prepared by partial reduction followed by acid hydrolysis of the ketal of the cyclohcptadecyne derivative 6 obtained by dehydrobromination of the dibromo ketal 5. ... 

Self-metathesis describes the reachon of an unsaturated fatty acid with itself. For example, methyl oleate gives a mixture of starting material (50%), unsaturated hydrocarbon (25%), and long-chain unsaturated diester (25%), aU as a mixture of T-and trani-isomers. (Figure 18). The diester can be converted to the musk component civetone, but a more efficient route is through self metathesis of the ketone oleon derived from methyl oleate by Claisen condensation (104) (Figure 18). 

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