Dihydrocinnamic alcohol

Phenethyl alcohol is qualitatively and quantitatively one of the most important fragrance substances that belongs to the class of araliphatic alcohols. Its lower homologue (benzyl alcohol) and higher homologue (dihydrocinnamic alcohol) also have characteristic odor properties, but are more frequently used in the form of their esters. Cinnamic alcohol, the most important unsaturated araliphatic alcohol, is valuable for both fragrances and flavors. 

High yields of cinnamic alcohol can be obtained by reduction of cinnamaldehyde with alkali borohydrides. Formation of dihydrocinnamic alcohol is thus avoided [146]. 

Cinnamaldehyde is used in many compositions for creating spicy and oriental notes (e.g., soap perfumes). It is the main component of artificial cinnamon oil. In addition, it is an important intermediate in the synthesis of cinnamic alcohol and dihydrocinnamic alcohol. 

The araliphatic alcohols mentioned above occur in many natural fragrances and flavors, but are generally not the main components. These alcohols are nearly always prepared synthetically for use in compositions. The branched-chain homolo-gues of phenethyl and dihydrocinnamic alcohols (dimethyl benzyl carbinol and dimethyl phenethyl carbinol, respectively) are used in fairly large amounts as fragrance materials, but have not been found in nature. 

Dihydrocinnamic acid. See Hydrocinnamic acid Dihydrocinnamic alcohol. See Hydrocinnamic alcohol... 

Synonyms Benzenepropanol 3-Benzenepropanol Benzylethyl alcohol Dihydrocinnamic alcohol Dihydrocinnamyl alcohol... 

Use 01 g. of the platinum oxide catalyst and 11 4 g, of pure cinnamic acid dissolved in 100 ml. of absolute alcohol. The theoretical volume of hydrogen is absorbed after 7-8 hours. Filter off the platinum, and evaporate the filtrate on a water bath. The resulting oil solidifies on cooling to a colourless acid, m.p. 47-48° (11-2 g.). Upon recrystallisation from light petroleum, b.p. 60-80°, pure dihydrocinnamic acid, m.p. 48-49°, is obtained. 

Charlton [57] demonstrated the use of oxazolidinones as effective chiral auxiliaries the commercially available (4i )-benzyl and (4S)-isopropyl-2-oxazolidinones were /V-acylated with dihydrocinnamic acid to give N-acyloxazolidinones (54 and 55) in yields greater than 80%, Scheme (10). Diastereoselective alkylation with tert-butylbromoacetate gave in each case principally only one diastereomer (56 and 57, respectively) (de>95%). The oxazolidinone moiety could be removed by utilizing LiOH-H2C>2 without affecting the tert-butyl ester. The crude acid was reduced to the corresponding primary alcohol with BH3THF, then... 

Cinnamic (1), p-coumaric (2), and related acids may be activated by conversion to CoA esters by CoA ligases [e.g., 4-coumarate CoA ligase (EC 6.2.1.12)] in much the same way that fatty acids are activated. The reduction of the CoA esters of cinnamic acids to cinnamyl alcohols involves two enz)mies cinnamoyl-CoA oxidoreductase (which forms the aldehydes) and cinnamyl alcohol dehydrogenase (Grisebach, 1981). Phenylpropanoids appear to be synthesized from the CoA esters of this series of acids by conversion to the corresponding aldehydes, then to the alcohols, and finally, by elimination of a phosphate group, to allyl and propenyl compounds. In many plants, mixtures of all t3q>es co-occur (Fig. 8.7) (Gross, 1981 Mann, 1987). Reduction of the side chain to produce dihydrocinnamic acids and related compounds is also known to occur in nature. 

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