Sandalwood odorants

Aldol reaction of the campholenic aldehyde with 2-butanone gives the intermediate ketones from condensation at both the methyl group and methylene group of 2-butanone (Fig. 6). Hydrogenation results in only one of the two products formed as having a typical sandalwood odor (160). 

Aldol reaction of campholenic aldehyde with propionic aldehyde yields the intermediate conjugated aldehyde, which can be selectively reduced to the saturated alcohol with a sandalwood odor. If the double bond in the cyclopentene ring is also reduced, the resulting product does not have a sandalwood odor (161). Reaction of campholenic aldehyde with -butyraldehyde followed by reduction of the aldehyde group gives the aHyUc alcohol known commercially by one manufacturer as Bacdanol [28219-61 -6] (82). 

When the a,P-unsaturated ketone is hydrogenated to the alcohol, a product with an intense sandalwood odor is produced (162). Many other examples of useful products have been made by condensation of campholenic aldehyde with ketones such as cyclopentanone and cyclohexanone. 

OC-Santalol. Sandalwood oil is comprised of mainly (90%) a- and P-santalol, which gives the oil the woody, tenacious sandalwood odor. An impure a-santalol [115-71 -9] (100) can be isolated by the distillation of the oil. P-Santalol [77-42-9] (101) is also isolated but ia much smaller amounts. The price of sandalwood oil, E. Indian, ia 1995 was 286/kg, and the oil from Indonesia was 187/kg (69). The high price of these oils has created the need to synthesize new materials with the sandalwood odor. The terpenophenols are manufactured by condensation of camphene with phenoHc compounds followed by hydrogenation to the cycloaUphatic alcohols (194). 

Kovatcheva, A., Buchbauer, G., Golbraikh, A., Wolschann, P. (2003) QSAR modeling of alpha-campholenic derivatives with sandalwood odor. T Chem Inf Comput Sci 43, 259-266. 

Some of the chemistry developed by the industry more recently, to produce new monohydric alcohols, is just as interesting as the linalool chemistry. Sandalore, a recent new Givaudan chemical with a persistent, sandalwood odor is made according to the scheme in Figure 15 (9). Alpha-pinene, the starting material, is converted to the epoxide which is catalytically rearranged to campholen-ic aldehyde. Aldol condensation with methyl ethyl ketone followed by hydrogenation yields Sandalore . 

PROP Mixture of a- and p-isomers from acetylation of santalol. Colorless to sidy yellow liquid sandalwood odor. D 0.980, refr index 1.488-1.491, flash p 212°F. Sol in ale insol in water. 

Even a cursory inspection of the known sandalwood odorants suggests a model that involves an alcohol function with a center of hydrophobic bulk at a set distance from it. This basic model has been refined by many workers that use different SAR techniques to define more closely the exact requirements of the hydrophobe and the distance between it and the alcohol function (55-60). Bajgrowicz et al. built an olfactophore model around this basic concept and used it to design a potent new sandalwood odorant successfully (61). 

Kovatcheva A, Buchbauer G, Golbraikh A, Wolschann P. QSAR Modelling of a-campholenic derivatives with sandalwood odor. J. Ghent. Nf. Comput. Sci. 2003 43 259-266. 

Neumann A,Weiss P, Wolschann P. A comparison of the molecular surfaces of sandalwood odorous molecules. Conformational calculations on sandalwood odor Vlll. J. Mol. Struct. 1993 296 145-152. 

Dimoglo AS, Beda AA, Shvets NM, Gorbachov MY, Kheifits LA, Aulchenko IS. Investigation of the relationship between sandalwood odor and chemical structure electron-topological approach. New J. Chem. 1995 19 149-154. 

Bajgrowicz JA, Frater G. Chiral recognition of sandalwood odorants. Enantiomer 2000 5 225-234. 

C13H24O, Mr 196.33, df 0.900-0.906, rag> 1.470-1.475, is a colorless liquid with a woody, tenacious sandalwood odor with a slight musk nuance. It is prepared by sequential aldol condensation of campholenaldehyde (2,2,3-trimethyl-3-cyclopentenea-cetaldehyde, obtained by epoxidation of a-pinene and rearrangement of the epoxide) with propanal, hydrogenation and reduction [106]. 

C13H22O, Mt 194.32, is not found in nature. It is a clear, colorless liquid, 0.919-0.929, Up 1.483-1.493, with a powerful sandalwood odor. It is prepared by condensation of campholenaldehyde with propionaldehyde and reduction of the formyl group. 

C14H24O, Mr 208.34, df 0.913-0.920, rag0 1.484-1.490, is a mixture of the cis and trans isomers. It does not occur in nature. It is a pale yellow liquid with a powerful sandalwood odor and a slight rose nuance. The mixture can be prepared starting from campholenaldehyde and butanal. The intermediate unsaturated aldehyde is partially hydrogenated to give the title alcohol. 

C14H24O, Mx 208.34, is a mixture of isomers and not reported as being found in nature. It is a pale yellow liquid with a powerful woody, sandalwood odor with musk aspect. The mixture is obtained by condensation of campholenaldehyde with 2-bu-tanone and isomerization of the reaction mixture with potassium ferr-butylate in dimethyl formamide. Subsequent reduction with NaBH yields a mixture of chiefly four diastereomeric title alcohols [108]. 

The mixture is used as such in large amounts as a fixative with sandalwood odor in a broad range of fragrances. 

Pale yellow somewhat viscid liquid characteristic sandalwood odor and taste. dg 0.965-0 980. aas —15 to —20 . njj 1.500-1 510. Very slightly sol in warer sol in 5 vols 70% alcohol. Keep well closed, cool and protected from light, Note West Indian sandalwood oil is derived from Amyris balsamifera and is not official. Its rotation is +24 to +29 . ll is less sol in 70% a]c than the East Indian, therap CAT Urinary anti-infective. 

CompositionThe main components are a- (ca. 50%) and santalols (ca. 20%). The latter component is responsible for the typical sandalwood odor. 

Synonyms Amyris balsamifera Amyris balsamifera oil Amyris oil Amyris oil. West Indian type Sandalwood oil Sandalwood oil. West Indian West Indian rosewood oil West Indian sandalwood oil Definition Produced by steam distillation of wood from Amyris balsamifera tree, contg. caryophyllene, cadinene, cadinol Properties Pale-yel. liq. sandalwood odor burning taste sol. in alcohol dens. 0.96 kg/l (20 C) ref. index 1.5035-1.5120(20 C)... 

Properties Colorless to pale yel. vise, oily liq., char, sandalwood odor and taste very sol. in fixed oils, propylene glycol sol. in 5 vols 70% alcohol very si. sol. in water insol. in glycerin m.w. 

Industrial Access to Some Sandalwood Odorants Through Chemoselective... 

Z)-beta-santalol (R)-alpha-campholenic aldehyde Fig. 6 Natural sandalwood odorant (—)-(Z)-beta-santalol and alpha-campholenic aldehyde... 

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