6-Methyl-3-heptene

Acid catalyzed dehydration of 2 2 dimethyl 1 hexanol gave a number of isomeric alkenes including 2 methyl 2 heptene as shown in the following formula... 

Kanasawud and Crouzet have studied the mechanism for formation of volatile compounds by thermal degradation of p-carotene and lycopene in aqueous medium (Kanasawud and Crouzet 1990a,b). Such a model system is considered by the authors to be representative of the conditions found during the treatment of vegetable products. In the case of lycopene, two of the compounds identified, 2-methyl-2-hepten-6-one and citral, have already been found in the volatile fraction of tomato and tomato products. New compounds have been identified 5-hexen-2-one, hexane-2,5-dione, and 6-methyl-3,5-heptadien-2-one, possibly formed from transient pseudoionone and geranyl acetate. According to the kinetics of their formation, the authors concluded that most of these products are formed mainly from all-(E) -lycopene and not (Z)-isomers of lycopene, which are also found as minor products in the reaction mixture. 

Taking advantage of this favorable equilibrium, 2-methyl-2-heptene was transformed to (Z)-3-methyl-3-octene with good selectivity 256... 

Epoxidation of (Z)-2-methyl-2-hepten-l-ol gave epoxy alcohol 61 (80% yield, 89% ee) [2], of (Z)-2-methyl-4-phenyl-2-buten-l-ol gave 62 (90%, 91% ee) 177], and of (2T)-1 -hydroxy squalene gave 63 (93%, 78% ee) [85]. The epoxy alcohol 64 had >95% ee after recrystallization [91], In the epoxidation of (Z)-2-r-butyl-2-buten-l-ol, the allylic alcohol with a C-2 r-butyl group, the epoxy alcohol was obtained in 43% yield and with 60% ee [38], These results lead one to expect that other 2,3Z-disubstituted allylic alcohols will be epoxidized in good yield and with enantioselectivity similar to that observed for the 3Z-monosubstituted allylic alcohols (i.e., 80-95% ee). 

The alkene mixture shown in the preceding equation constitutes part of the answer to part (b). None of the alkenes arising from methyl migration is 2-methyl-2-heptene, the answer to part (a), however. 

Figure 5 shows the thermally induced hydrolytic degradation of citral (geranial and neral) into 2-methyl-2-hepten-6-one and acetaldehyde. It is similar to the reaction mechanism as proposed by Josephson and Lindsay (22, 23). The relatively higher amount of 2-methyl-2-hepten-6-one and the concomitant lower amount of geranial and neral in steam distilled oil confirmed again a previous report (24). 

Figure 5. Thermally induced hydrolytic degradation of citral (geranial and citral) into 2-methyl-2-hepten-6-one and acetaldehyde.

The PTC method gives poor results with trisubstituted and 1,1-disub-stituted olefins. The oxyamination product may still form, but it is accompanied by a number of by-products. Fortunately, this class of olefins is successfully oxyaminated by the alternative procedure (B). Methyl-cyclohexene, a-methylstyrene, 2-methyl-2-hepten-6-one, and its ketal are examples of olqfins that give oxyamination products in good yield following procedure B. 

By the Carroll rearrangement, 2-methyl-2-hepten-6-one (8.34) from commercially available materials such as acetone, acetylene and ethyl acetoacetate is synthesized (Scheme 8.13). 

C8H1403 ethyl 5-oxohexanoate 13984-57-1 494.65 43.370 1,2 14752 C8H15CI 6-chloro-2-methyl-2-heptene 80325-37-7 441.98 37.415 2... 

C8H16 2-methyl-2-heptene 627-97-4 160.38 15.368 2 14984 C8H16 4-methyl-3-ethyl-trans-2-pentene 42067-49-2 145.38 11.845 2... 

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