Ambergris oxide

Ambergris oxide (Ambrox ) is one of the most important ambergris fragrance compounds and is a key compound of ambra, a secretion product of the... 

The fragrance (-)-Ambrox (a commercial substitute for ambergris from the blue sperm whale) was made by oxidation of (-)-sclareol (1) with RuClj/aq. Na(IO )/ CC1 -CH3CN/40°C a mixture of (+)-sclareolide (2) with the (-)-acetoxy acid... 

Cistus and labdanum products come from Mediterranean countries, mainly Spain, where the Cistus shrub grows abundantly. They are used widely in perfumery, giving perfume compositions a warm, balsamic tonality with a touch of ambergris. The typical odor originates from a number of compounds which are formed by oxidative degradation of diterpenes with labdane skeleton, which are the main constituents of labdanum gum [284a, 558 565aj. The resinoids and absolutes are excellent natural fixatives. FCT 1976 (14) p.335 [8016-26-0], [89997-74-0]. 

In addition to linalyl acetate, the oil contains linalool and other terpene alcohols, as well as their acetates. When the volatile components are evaporated, a distinct ambergris note develops that is attributed to oxidative degradation products of sclareol [515-03-7] [746-750a]. Sclareol is the main component in the concrete, obtained by solvent extraction of S. sclarea L. leaves [750b]. 

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, ner-ol 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, slightly ambergris-like odor, can be prepared by treatment of -caryophyllene with organic peracids. a-Cedrene oxide [11000-57-0] is another wood-fragrance compound, which can be easily prepared by epoxidation of cedarwood oil hydrocarbons. 

Racemic sclareolide is prepared in another industrial process by cyclization of homofarnesic acid in the presence of SnCh as a catalyst [184], Pure diastereomers are obtained by acid cyclization of trans- and c/s-4-methyl-6-(2,6,6-trimethylcyclo-hex-l(2)-enyl)-3-hexen-l-ol, prepared from 2-methyl-4-(2,6,6-trimethylcyclohex-l(2)-enyl)-2-butenal [185], If the racemic sclareolide mixture is resolved into its enantiomers, the (-)-oxide may also be obtained by a totally synthetic route [185a], [185b], The product is used in perfumery for creating ambergris notes. 

The oxidation of manool has been re-examined with the aim of producing ambergris-type perfumes. Oxidation with potassium permanganate afforded the known s methyl ketone (6), the diether (7), and at 40 °C the lactone (8). Sodium dichromate gave the aldehyde (9) as a mixture of E- and Z-isomers. Further oxidation of the methyl ketone with hypobromite gave an a-hydroxy-acid (10) and an ether (11) which was also obtained from manoyl oxide. Oxidation of the ketone with per-acid gave an acetoxy-epoxide which on reduction with lithium aluminium hydride afforded a diol. This was converted into an odoriferous ether (12). The ready formation of 5- and 6-membered-ring ethers of this type is a characteristic feature of this area of diterpenoid chemistry. 

Jeger s ketal (394), named after its discoverer, but also called Amberketal, Ambrake-tal, and Ketamber, is another material with a powerful ambergris odor. It is prepared from manool (395), extracted from the New Zealand tree Dacrydium biforme, by permanganate oxidation to the ketone (396) followed by osmylation of the double bond and spontaneous formation of the ketal from the resultant diol-ketone. It has also been synthesized from larixol (397), which is readily available from the European larch, Larix decidua 449). 

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