Cis-2-Hexene

When epoxides such as tra s-3-hexene-epoxide 1885 are heated to 65 °C with hexamethyidisiiane 857 and potassium methoxide in anhydrous HMPA, trimethylsilyl potassium 1882 is generated in situ to open the epoxide rings and give 1886, which subsequently looses potassium trimethylsilanolate 97 to afford olefins with inverted stereochemistry, for example as cis-3-hexene 1887, in high yield [103]. The reaction also proceeds at 65 °C in THF, rather than HMPA, if 18-crown-6 is added [103a] (Scheme 12.29). 

A very large number of volatile substances have been identified in fresh tea leaf.64 Substances present at the highest levels include the ubiquitous leaf aldehyde, trans-2-hexenal, and leaf alcohol, cis-3-hexenol. Both arise from cis-3-hexenal, which is biosynthesized from linoleic acid in leaf as a result of enzymic splitting.65... 

Thermochemical data from the compilation of Stull et at., 1969. Entropy values are based on a 1 M standard state. The asterisk denotes symmetry-corrected quantities. Symmetry numbers were chosen as follows 18 for the n-alkanes, cis-3-hexene, dibuthyl sulphide, diethyl ether, and diethyl amine 2n for the cycloalkanes and 2 for all of the remaining ring compounds 3 for the alkanols, alkanethiols and alkyl amines 9 for the methyl alkyl sulphides... 

Alkynes are hydrogenated to cis olefins with the same catalytic systems, and subsequently undergo hydrogenation to yield the corresponding alkanes [7, 42, 45, 47, 49, 59, 93]. For example, Jordan et al. reported the selective hydrogenation of 3-hexyne into cis 3-hexene with a TOF of 25 IT1 [25], and cis 3-hexene is... 

HEXENE cis-2-HEXENE trans-2-HEXENE cis-3-HEXENE trans-3-HEXENE METHYLCYCLOPENTANE... 

Dzhavelidze, T. A. Phenolic compounds in various parts of tea shoots. Subtrop Kult 1978 1978 154-155. Hatanaka, A., T. Kajiwara and J. Sekiya. Biosynthesis of leaf alcohol the oxygenative cleavage of linolenic acid to cis-3-hexenal and 11-formyl-cis-9-undecenoic acid from linolenic acid in tea chloroplasts. Symp Chem Nat Prod-22nd- Fukuoka, Japan 1979 657-664. 

Figure 3. Components trapped from the air over cut potato leaves. Carbon traps were extracted with 60 fxL of CSt IftL was used for CC (detector FID). GC conditions WCOT Carbowax 20M column, 50 m long temperature programmed 70-150 °C. Key a, trans-2-hexenal b, cis-3-hexenyl acetate c, cis-3-hexen-l-ol and d, tians-2-hexen-l-ol (14).

Figure 5. Mean EAG responses of three male and three female Colorado beetles from different populations to tta.ns-2-hexen-l-ol (t-2-H-l-ol), cis-3-hexen-l-ol (c-3-H-l-ol), ds-3-hexenyl acetate (c-3-H-ace), and tra.ns-2-hexeruil (t-2-H-al) at two dilutions in paraffin oil, 10 and 10 (v/v). Key A, laboratory stock culture B, field population Wageningen C, field population Utah vertical lines indicate 95% confidence intervals and, significant a/ P < O.OI (Mann-lVhitney V test).

Leaf odours. The total essence which emanates from growing leaves is not solely constituted of straight chain alcohols and aldehydes. In the insect s selection of a host plant, species-specific components might be involved. The leek moth Acrolepiopsis assectella is attracted by thiosulfinates, compounds isolated from leek. Cis-3-hexen-1-ol was also shown to be attractive (27). 

Figure 7. Intensity of neural activity in 23 olfactory receptor cells in the antenna of the Colorado beetle, in response to tTins-2-hexen-I-ol (t-2-H-I-ol), cis-3-hexen-I-ol (c-3-H-I-ol), and Uins-2-hexenal (t-2-H-al). The increase of neural activity in response to individual green odor components is visualized in the areas of circles...

Figure 10.5 (a) Gas chromatogram obtained from a natural cis-3-hexen-l-ol fraction after... 

Figure 15.12 GC-GC chromatogram of a natural cw-3-hexen-l-ol fraction. Peak identification is as follows 1, ethyl-2-methylbutyrate 2, trans-2-hexenal 3,1-hexanol 4, cis-3-hexen-l-ol 5, frmw-2-hexen-l-ol. Adapted from Journal of High Resolution Chromatography, 15, S. Nitz el al., Multidimensional gas chromatography-isotope ratio mass spectrometry, (MDGC-IRMS). Part A system description and technical requirements , pp. 387-391, 1992, with permission from Wiley-VCH.

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