Z-a-Pinene

Alloocimene Manufacture. a-Pinene (8) is converted thermally first to cis-ocimene (17), which rearranges to give about 40—50 wt % of the two alloocimene isomers, ie, alloocimene [7216-56-0] (53) and 4-trans-(i-trans-2S[oo[Pg.417]

It contains Z-a-pinene, about 10 per cent, of eucalyptol, pheUandrene, eudesmol, and a sesquiterpene. 

It contains Z-a-pinene, Z-limonene, hornyl acetate, lauric aldehyde, probably traces of decyl aldehyde, and the hydrocarbon santene, CjHj. An oil is also distilled from the young cones of this tree. It contains more terpenes than the leaf oil, and has the following characters — 

An alternative route to Z-(-)-carvone (20) was developed from the more abundant (-)-a-pinene (2), albeit a somewhat lower overall yield (Scheme 5.7).36 The process involves hydroboration of 2 followed by oxidation of the resultant alcohol. Subsequent treatment of the /-isopinocamphone 

The reaction of the (Z)-crotyldiisopinocampheylborane derived from (+-)-a-pinene with aldehydes at -78 °C, followed by oxidative workup, furnishes the corresponding j yn-P-methylhomoallyl alcohols with 99% diastereoselectivity and 95% enantioselectiv-ity. Use of (Z)-crotyldiisopinocampheylborane derived from (-)-a-pinene also produces 5yn-alcohols with 99% diastereoselectivity but with opposite enantioselectivity, an example of reagent control. 

That the oil contains the following constituents, Z-a-pinene, d-a pinene, Z-limonene, Z-borneol, bornyl acetate and other esters of bomeol, Z-camphor, cineol, salicylic acid, aldehydes, formic, acetic, butyric ( ) and isovaleric acids, a non-volatile acid or lactone, and a blue constituent of high boiling-point. 

Among the aldehydes isolated from the oil methyl-vanillin was found, which had never previously been found in an essential oil. Citral, Z-a-pinene, and methyl-isoeugenol are also present in the oil. 

Crotyldlisopinocampheylborane. IpC2BCH2CH=CHCH3 (1). The (Z)-isomer is prepared by reaction of (Z)-crotylpotassium with methoxydiisopinocampheylbo-rane [obtained from (- )-a-pinene] to form an ate complex, which is converted into (Z)-l on reaction with BF3 etherate at -78°. The (E)-isomer is prepared similarly from (E)-crotylpotassium. Reaction of acetaldehyde with (Z)-l at - 78° results in (2S,3S)-3-methyl-4-pentene-2-ol (2) in 99% diastereoselectivity and 95% enantioselectivity (equation I). A similar reaction with (E)-l provides (2S,3R)-2. 

Composition According to ISO [19], the oil contains 86-95% E-anethole, up to 1.0% Z-anethole and up to 6.0% methyl chavicol. Eoeniculin can occur up to 3.0%, anisic aldehyde is limited to 0.5%. Further constituents are monoterpenes like a-pinene, a-phellandrene, limonene, linalool and a-terpineol. Besides P-caryophyllene, two further sesquiterpenes are typical trace components for Chinese star anise oil, namely E-and Z-a-bergamotene. 

GC—O experiments of a waxed and oiled parquet floor revealed acetaldehyde, methyl propanal, 3-methyl butanal, pentanal, hexanal, heptanal, a-pinene, 1-octen-3-one, 3-pinene, octanal, l-nonen-3-one, nonanal, Z-2-nonenal and E-2 nonenalas the most important odorants (Mayer, Breuer and Mayer, 2000). In contrast the less intense odor of varnished parquet floor was mostly caused by acetaldehyde, butanal, 3-methyl butanal, pentanal, hexanal, a-pinene, benzaldehyde, l-octen-3-one, P-pinene and acetophenone. 

Approximately 230 volatile compounds have been identified in raspberry fruit [35]. The aroma of raspberries is composed of a mixture of ketones and aldehydes (27%) and terpenoids (30%), alcohols (23%), esters (13%) and furanones (5%). The raspberry ketone (Fig. 7.5) along with a-ionone and jS-ionone have been found to be the primary character-impact compounds in raspberries. Other compounds such as benzyl alcohol, (Z)-3-hexen-l-ol, acetic acid, linalool, geraniol, a-pinene, jS-pinene, a-phellandrene, jS-phellandrene and jS-caryophyllene contribute to the overall aroma of mature red raspberries [101-105]. The most important character-impact compounds of raspberries are summarised in Table 7.3. 

To a stirred — 78 C solution of 5.85 mL (62.5 mmol) of 3-methoxy-l-prnpene in 25 mL of THf- are added 43.1 mL (50 mmol) of 1.16 M. vcc-butyllithium in cyclohexane over a 20-25 min period. The mixture is stirred at — 78 °C for an additional 10 min, and diisopinocampheyl(methoxy)borane [50 mmol prepared from (+ )-a-pinene] in 50 mL of THF is added. This mixture is stirred for 1 h, then 8.17 mL (66.5 mmol) of boron trifluoride diethyl etherate complex are added dropwise to give a solution of diisopiuocampheyl[(Z)-3-inethoxy-2-propenyl]borane. Immediately. 2.8 mL (50 mmol) of acetaldehyde are added and the mixture is stirred for 3 h at — 78 rC and then allowed to warm to r.t. All volatile components are removed in vacuo, then the residue is dissolved in pentane. The insoluble fraction is washed with additional pentane. The combined pentane extracts are cooled to 0 JC and treated with 3.0 mL (50 mmol) of ethanolamine. The mixture is stirred for 2 h at 0rC and is then seeded with a crystal of the diisopinocampheylborane-ethanolaminc complex. The resulting crystals arc filtered and washed with cold pentane. The filtrate is carefully distilled yield 5.6 g (57%) d.r. (synjanti) >99 1 (2/ ,37 )-isomer 90% ee bp 119-120 C/745 Torr. 

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