3.5- Heptadien-2-one

Still another possibility of isomerization is illustrated by the easy interconversions between pentaphenylpentadienoie aeid chloride and 2-chloropentaphenyl-3-eyelopenten-l-one. Interestingly, 2,4,6-trimethylpjrrylium iodide maj be sublimed without decomposition in a vacuum, possibly as a covalent 6-iodo-4-methyl-3,5-heptadien-2-one or 2-iodo-2,4,6-trimethyl-2H-pyran valenee isomer. In a related case, chlorocyclopropenes are covalent and are converted into cyclo-propenium derivatives only by the action of Friedel-Crafts catalysts (electron-deficient metallic chlorides) (ef. also Section II,C, 2,c.)... 

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. 

Nucleophilic 1,4- and 1,6-additions of cuprates and other organometallic reagents to acceptor-substituted dienes have been utilized extensively in target-oriented stereoselective synthesis52-61. Schollkopf and coworkers55 reported the diastereoselective 1,6-addition of a bislactim ether-derived cuprate to 3,5-heptadien-2-one (90% ds equation 17). The corresponding reactions of dienoates were conducted with the lithiated bislactim ether and proceeded with diastereoselectivities of >99% ds (equation 18)56 the adducts could be converted easily into diastereo- and enantiomerically pure amino acid derivatives. 

Ethylcyclop entanon e 3-Pentyl cyclopentanone 6-Methyl-3,5-heptadien-2-one 6-Methyl-2-cyclohexen-l-one 2,3-Dihydrocarvone Unidentified dimethylacetophenone 2-Butyrylfuran Dimethyl disulfide 2,6-Dimethylpyridine Isobutylbenzene Unidentified acetal (mol mass 154) Isobutyronitrile... 

Dimethyl-y-pyrone reacts with sodium selenide (or sodium hydrogen selenide) to give 2,6-dimethyl-4-seleno-y-pyrone (66). This, in turn, reacts with sodium selenide to give 4,6-bis(hydroseleno)-3,5-heptadien-2-one (67), which is readily oxidized by air to 5-methyl-l,2-diselenol-3-yIidene acetone (68).84,85... 

In the case of multiply unsaturated carbonyl compounds, regioselectivity is also sensitive to the nature of the catalyst, to reaction conditions, and to the structure and degree of substitution of the hydrogenated double bonds. For example, hydrogenation of 3,5-heptadien-2-one over nickel on alumina or nickel on zinc oxide occurs mainly at the y,8-double bond. But if the catalyst is modified by the addition of lead or cadmium, reduction occurs mainly at the a,p-double bond (Scheme 24). 

The selectivity may be oriented toward reduction of the a,)3-unsaturation of conjugated dienones, e.g., hydrogenation of 6-methyl-3,5-heptadien-2-one, 21, over Ni-on-alumina or Ni-on-Zn oxide results in saturation of the S-double bond to give 22, but modification of the catalyst by addition of Cd forms 23 ... 

Methylheptadecyl 16-methyl heptadecanoate. See Isostearyl isostearate Methyl heptadienone 2-Methyl hepta-2,4-dien-6-one. See 6-Methyl-3,5-heptadien-2-one 6-Methyl-3,5-heptadien-2-one CAS 1604-28-0 EINECS/ELINCS 216-507-7 Synonyms Methyl heptadienone 2-Methyl hepta-2,4-dien-6-one 6-Methylhepta-3,5-dien-2-one... 

Methyl eugenol Methyl 2-furoate 6-Methyl-3,5-heptadien-2-one... 

Methyl n-amyl ketone Methyl anthranilate Methyl benzoate a-Methylbenzyl acetate a-Methylbenzyl alcohol Methyl cinnamate 3-Methyl-2-cyclopenten-2-ol-1-one 6-Methyl-3,5-heptadien-2-one Methyl a-ionone Methyl isoeuqenol Methyl laurate 1-Methyl-1-methoxycyclododecane Methyl 2-nonenoate Methyl nonyl acetaldehyde Methyl 2-octynoate Methyl pelarqonate Methyl phenylacetate Methyl salicylate Methyl tiqiate Methylundecanal dimethyl acetal Myrcene Nerol... 

Although the number of aroma compounds derived from acyclic carotenoids is much inferior to that of the mono- and bicyclic compounds, some of them can also be considered as breakdown products from genuine mono-, sesqui- and diterpenoids. The importance of the aliphatic isoprenoids (282) to (291) in the formation of total flavors of certain foodstuffs is not less than that of the cyclic compounds, the three methyl ketones (282), (287) and (290) which are related to the main tomato pigment lycopene were observed in tomato flavor (75). The hexahydro derivative (291) from coffee (595), jasmine oil (722) and green tea 438) is perceived as flowery and warm and can be considered as an oxidative biodegradation product of phytol and phyta-diene. 6-Methyl-3,5-heptadien-2-one (283), with a grassy and cinnamonlike aroma 438) [detected in tomato 668), the essential oil of Hama-metis leaves 383), Ceylon tea (722) and passion fruit (777)], and pseudo-ionone (288) [also isolated from passion fruit (777)] are believed to be formed from two different dehydrolycopenes. Compounds other than carotenoids, such as solanesol or squalene, can also be considered... 

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