1,7-Octadiene-3-one

The important intermediate 66 of the steroid synthesis has been prepared by the application of the same reaction sequence to 2-methyl-1,3-cyclohexanedione (65) (Scheme 22). A synthesis of (+) 19-nortestosterone (69) starts with the Michael addition of the optically active oxo ester 67 to 1,7-octadien-3-one (59) catalyzed by sodium hydride, the ester group being removed by heating in aqueous HMPA with sodium iodide to give the dione 68. The aldol condensation catalyzed by sodium hydroxide proceeds in 90% yield. The terminal double bond is oxidized with PdCl2/CuCl to the methyl ketone and the internal olefinic double bond subsequently hydrogenated. The final reaction step involves aldol condensation in refluxing... 

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. 

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-... 

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. 

The oxidation of arachidonic acid, which is present in low amounts in meat and especially in egg yolk, can in principal generate the same compounds as linoleic acid. Additionally, aldehydes with more than 10 carbons are formed, e.g. 2,6( , Z)-dodeca-dienal and 2,4,7( , Z,Z)-tridecatrienal [60, 62], Typical reaction products with low odour thresholds from linolenic acid are 2( )-hexenal, 2,6( , Z)-nonadienal and 1,5(Z)-octadien-3-one. 

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. 

Methylenenorbornene behaves like NBD while 1,7-octadiene affords the same triplet with intermediate intensity between that of NBE and NBD. In one experiment where neat NBD was added to the usual solution of I in CH2CI2 almost clear polymer formed and swelled up in the epr sample tube above the purple solution of I at the bottom. This solution showed the usual triplet, but when the tube was lowered further into the epr cavity so that the polymer could now be analysed, a weak but very clear quartet (1 3 3 1) of triplets is observed, Figure 5. 

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-... 

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). 

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. 

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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