L,7-Octadiene-3-one

Acetoxy-l,7-octadiene (40) is converted into l,7-octadien-3-one (124) by hydrolysis and oxidation. The most useful application of this enone 124 is bisannulation to form two fused six-membered ketonesfl 13], The Michael addition of 2-methyl-1,3-cyclopentanedione (125) to 124 and asymmetric aldol condensation using (5)-phenylalanine afford the optically active diketone 126. The terminal alkene is oxidi2ed with PdCl2-CuCl2-02 to give the methyl ketone 127 in 77% yield. Finally, reduction of the double bond and aldol condensation produce the important intermediate 128 of steroid synthesis in optically pure form[114]. 

Acetoxy-l,ll-dodecadien-3-one (17) is a synthetic equivalent of 1-dodecene-3,7,11-trione (18), and prepared from l,7-octadien-3-one (16), which is obtained from the butadiene telomer 15 (see Section 5.2). The acetoxy group and the double bond in 17 are precursors of two carbonyl groups. The reagent 17 is used for steroid synthesis. 

A new synthetic method for steroids has been developed using a butadiene dimer (66) as a building block and the palladium-catalyzed oxidation as the key reaction.3-Acetoxy-l,7-octadiene (66), prepared by the palladium-catalyzed reaction of butadiene with acetic acid, is hydrolyzed and oxidized to l,7-octadien-3-one (67) in high yield. The enone (67) is a very useful reagent for bisanellation because its termiiud double bond can be regarded as a masked ketone which can be readily unmasked by the palladium catalyst to form the l,S-diketone (68) after Michael addition at the enone moiety of (67 Scheme 20). Thus, the enone (67) is the cheapest and most readily available bisanellation reagent, permitting a simple total synthesis of steroids. 

Tsuji and colleagues have synthesized l,7-octadiene-3-one 62 from the readily available butadiene telomer 59 ° and have explored the utility of 62 in natur product synthesis, including two routes to 19-norsteroids. ... 

This methodology has also been applied to the synthesis of CD rings of steroids 117, first by Tsuji et al. and then by others (Scheme 23). The trisannnlation reagent 115 prepared from l,7-octadien-3-one and ( )-3-oxo-8-phenoxy-6-octanoate was snbjected to cyclization nnder nentral conditions to give cyclopentanone 116. Construction of the CD... 

This alcohol can also be dehydrogenated, and the reaction is catalyzed by Cu/Zn alloy, yielding the l,7-octadien-3-one, a very useful bis-annelation reagent. This compound enables the simple synthesis of important intermediates in steroid chemistry, as outlined in Equation 9. 

In Scheme 26.24, examples of an RCM/isomerization/tautomerization sequence by Yoshida et al. are shown [30]. After RCM of 4-methylene-l,7-octadien-3-ones 81, synthesis of phenols 83 was accomplished by Rh-catalyzed isomerization of the carbon-carbon double bond of the RCM products 82 from exo to endo, followed by spontaneous tautomerization. The same group also showed that the Mizoroki-Heck reaction could be used as an alternative to the isomerization described above (Scheme 26.25) [30]. In the presence of a catalytic amount of Pd(OAc)2, RCM product 82... 

Oxidized fish oils, rich in n-3 polyunsaturated fatty acids, produced volatile compounds more readily than oxidized vegetable oils, rich in linoleic acid. Activation energy for the formation of propanal from fish oils was lower than for the formation of hexanal from vegetable oils. A mixture of aldehydes contributed to the characteristic odors and flavors of oxidized fish, described as rancid, painty, fishy and cod liver oil-like (Table 11.21). Oxidation of unsaturated fatty acids in fish was related to the formation of 2-pentenal, 2-hexenal, 4-heptenal, 2,4-heptadienal and 2,4,7-decatrienal. The fishy or trainy characteristic of fish oil was attributed to 2,4,7-decatrienal. Studies of volatiles from boiled trout after storage showed significant increases in potent volatiles by aroma extraction dilution analysis (Table 11.22). Volatiles with the highest odor impact included l,5-octadien-3-one, 2,6-nonadienal, 3-hexenal, and 3,6-nonadienal. 3,6-Nonadienal and 3-hexenal were considered to contribute most to the fatty, fishy flavor in stored boiled fish. 

Trimethylamine also has a fishy odor. However, its odor threshold at the pH of fish meat is very much higher than that of the potent lipid peroxidation products, e. g., (Z)-l,5-octadien-3-one (cf. 3.7.2.1.8 and 11.2.4.4.4). Therefore, it plays a role as an off-flavor substance only on stronger bacterial infection of fish at temperatures >0 °C. 

Carbowax 20M (Union Carbide, Danbury, CT, U.S.A.) on 120-140 mesh Chromosorb G (Johns Manville, NY, U.S.A.)). Trans- and c -4,5-epoxy-(ii)-2-decenal were synthesized by epoxidation of (E,E)- and E,7)-2,4-decadienal, respectively, using 3-chloroperoxybenzoic acid [3]. (Z)-l,5-Octadien-3-one was synthesized, following procedures described by Swoboda and Peers [4]. Diethyl ether was freshly distilled every 4wk and stored in the dark after addition of antioxidant 330 (l,3,5-trimethyl-2,4,6-tris-[3,5-di-tert-butyl-4-hydroxybenzyl]-benzene). 

Linalool (3,7-dimethyl-l,6-octadien-3-ol) (62) occurs as one of its enantiomers in many essential oils, where it is often the main component. (/ )-(-)-Linalool for example occurs at a concentration of 80-85% in Ho oils from Cinnamomum camphora rosewood oil contains ca 80%. (S)-(+)-Linalool makes up 60-70% of coriander oil [26]. 

Let us next consider the possible biogenetic pathways of conversion products formed from linalool by I3 cinerea. One could assume that 2,6-dimethyl-3,7-octadiene-2,6-diol (29) and 2,6-dimethyl-1,7-octadiene-3,6-diol (30) (Figure 6), both detected among the natural grape must constituents (cf. Figure 1-1), function as intermediates in the formation of 2,6-dimethyl-2,7-octadiene-l,6-diols (19) and (20). However, in control experiments, in which the diols (29) and (30) were added to the botrytized must instead of linalool, no formation of (19) or (20) could be observed. Consequently, for the production of (E)-2,6-dimethyl-2,7-octadiene-... 

Other phytochemicals which exhibit JH activity include juvadecene (1-(3,4-methylenedioxyphenyI)-fraws-3-decene) isolated from roots of the pepper-tree, Macropiper excelsum Miq. [110], thujic acid (5,5-dimethyl-1,3,6-cycloheptatrien-l-carboxylic acid) extracted from the heartwood of western red cedar, Thujaplicata [111] andtagetone((E)-2,6-dimethyl-5,7-octadien-4-one) from the marigold, Tagetes minuta L. [112], There have been numerous reports of juvenoid activity of plant extracts (Table 5) however, to our knowledge, the compound(s) responsible for this activity have not been isolated and characterized. 

Other carbonyls cis-4-heptenal, trans,cw-2,6-nonadienal, 2,5-octadienal, 2,4,6-nonatrienal, 2,4,7-decatrienal, l-penten-3-one, l-octen-3-one,tra/ts,cw-3,5-octadien-3-one,3,5-undecadien-3-one, 1-octen-... 

The biotransformation of linalool by Botrytis cinerea has also been described [60]. After addition of linalool to botrytised must, a series of transformation products was identified (E)- (49) and (Z)-2,6-dimethyl-2,7-octadiene-l,6-diol (48), trans- (76) and cw-furanoid linalool oxide (77), trans- (78) and c/s-pyranoid linalool oxide (79) and their acetates (80, 81), 3,9-epoxy-p-menth-1 -ene (75) and 2-methyl-2-vinyltetrahydrofuran-5-one (66) (unsaturated lactone), Fig. (11). Quantitative analysis however, showed that linalool was predominantly (> 90%) metabolised to ( )-2,6-dimethyl-2,7-octadiene-l,6-diol (49) by B. cinerea. The other compounds were only found as by-products in minor concentrations. 

Tris(pentafluorophenyl)borane (BCCgFj), purity 97%) was obtained from Lancaster, dimethoxydimethylsilane (DMDMS) from PCR, 1,1,3,3-tetramethyldisiloxane (L H, purity 97%) from ABCR, the methoxydimethylsilane (MDMS) from Fluorochem and 1,7-octadiene (purity 98%) from Aldrich. AU of them were used without any further purification. All solvents were pnrchased from Aldrich and anhydrons tolnene was stored over sodium. During the varions experiments we used two batches of catalyst. Since the first one contained a fair amonnt of water, a small content of Brij 98 (from Aldrich), a non-ionic surfactant, was added, so that the ethylene glycol functions competed with water to complex B(C Fj)3 and to increase its activity. 

These fungal conversion products comprised (E)- (19) and (Z)-2,6-di-methyl-2,7-octadiene-l,6-diol (20), the furanoid (Z)- (21) and (E)-linalool oxides (22), the pyranoid (Z)- (23) and (E)-linalool oxides (24), their isomeric acetates (25) and (26), 3,9-epoxy-p-menth-l-ene (27) and 2-vinyl-2-methyl-tetrahydrofuran-5-one (28). 

One of the important advantages of using benzobjcyclooctene models in comparison with bicycloheptene ones is the relative ease of establishing the intermediate formation of a classical or nonclassical carbocation by the stereochemistry of the products formed. It is clearly seen from the chlorination of benzobicyclo[3,2,l]-octadienes. If the chlorination of derivatives of 6,7-tetrafluorobenzobicyclo[3,2,l]-octadiene first yields an exo-halogenonium ion, then the participation of the aromatic ring and of the o-bond 1-7 turns out to be effective enough to direct the... 

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