Decadienal, 2.4-. formation

Based on a similar approach, Backvall403 established the stereochemical course of such reactions and developed efficient routes to bicyclo[4.3.0]-nonadiene and bicyclo[5.3.0]-decadiene systems. Backvall404 has also reported a Pd(02CCF3)2-catalyzed oxidative carbocyclization of allenenes (Scheme 125). The process is efficient even with catalyst loading as low as 1 mol%, although if requires/>-benzoquinone as the stoichiometric oxidant, which represents the first example of a C-C bond formation using a catalytic amount of Pd(ll). Bicyclic adducts have been obtained in... 

When the pyrone 297 was exposed to base in dichloromethane, formation of the oxidopyrylium occurs and subsequent cycloaddition transpires. Lee found that when the allene tether was 3 (n = 0), cycloaddition occurs to form the bicy-clo[5.3.0]decadiene 298 exclusively, rather than the alternative bicyclo[5.2.0] nonadiene product 299. Increasing the tether length by one resulted in formation of the exo-substituted double bond (299) in 45% yield. Increasing the tether length by one carbon, to four, completely retarded the cycloaddition (Scheme 4.83). 

Mori has reported the nickel-catalyzed cyclization/hydrosilylation of dienals to form protected alkenylcycloalk-anols." For example, reaction of 4-benzyloxymethyl-5,7-octadienal 48a and triethylsilane catalyzed by a 1 2 mixture of Ni(GOD)2 and PPhs in toluene at room temperature gave the silyloxycyclopentane 49a in 70% yield with exclusive formation of the m,//7 //i -diastereomer (Scheme 14). In a similar manner, the 6,8-nonadienal 48b underwent nickel-catalyzed reaction to form silyloxycyclohexane 49b in 71% yield with exclusive formation of the // /i ,// /i -diastereomer, and the 7,9-decadienal 48c underwent reaction to form silyloxycycloheptane 49c in 66% yield with undetermined stereochemistry (Scheme 14). On the basis of related stoichiometric experiments, Mori proposed a mechanism for the nickel-catalyzed cyclization/hydrosilylation of dienals involving initial insertion of the diene moiety into the Ni-H bond of a silylnickel hydride complex to form the (7r-allyl)nickel silyl complex li (Scheme 15). Intramolecular carbometallation followed by O-Si reductive elimination and H-Si oxidative addition would release the silyloxycycloalkane with regeneration of the active silylnickel hydride catalyst. 

The structure of the products and a reasonable mechanism of formation are shown in Eq. (59). The ester function is found only in the C-l position of the open-chain product, and it is therefore probable that only one cyclo-decadiene isomer, m,/raws-3,7-CDD-l-carboxylic acid ester (LXIIIa), is formed. However, the thermal Cope rearrangement of (LXIII) leads to... 

Aldehyde Formation. Several investigators observed a marked dominance of hexanal in the volatile products of low-temperature oxidation. At the higher temperatures, however, 2,4-decadienal was the major aldehyde formed (19,20,21). Both aldehydes are typical scission products of linoleate hydroperoxides. Swoboda and Lea (20) explained this difference on the basis of a selective further oxidation of the dienal at the higher temperature, while Kimoto and Gaddis (19) speculated that the carbon-carbon bond between the carbonyl group and the double bond (Type B) is the most vulnerable to cleavage under moderate conditions of autoxidation, while scission at the carbon-carbon bond away from the olefinic linkage (Type A) is favored under stress such as heat or alkali. 

N-Heterocyclics. The reaction of primary amines with the carbonyl products derived from lipid oxidation is a major pathway in lipid-protein interactions. Formation of Schiff s base intermediates followed by cyclization and rearrangement can yield imines, pyridines and pyrroles (5,15,30,31). For example, 2-pentylpyridine may result from the reaction of ammonia with 2,4-decadienal, one of the principle aldehydes from the autoxidation of linoleate (5). 

Another interesting group of heterocyclic compounds formed in the reaction of 2,4-decadienal and cysteine is the thiophenes. Thiophenes having butyl to heptyl groups substituted at the 2-position were identified. Mechanisms have been suggested for the production of thiophene derivatives by the action of hydrogen sulfide on 1,4-dicarbonyl compounds (24). The exact mechanism for the formation of thiophenes in this system is not clear and deserves more study. 

The amount of 2-pentylpyridine generated in the 2,4-decadienal/ glutathione system was greater than that in the 2,4-decadienal/ cysteine system. It is known that the formation of dithiazine or thiadiazine requires the presence of free ammonia. The absence of formation of dithiazine or thiadiazine in the 2,4-decadienal/glu-tathione system indicates that no free ammonia is available. This strongly suggests that the formation of 2-pentylpyridine does not require the presence of free ammonia. It is possible that the amino... 

The flavor compounds of the crust from the chemically leavened model bread were then compared to those recently identified (6) in the crust of a standard wheat bread which was leavened by addition of yeast (Table I). One striking difference was that Acp (No. 16), which showed the highest FD-factor in the yeast-leavened bread showed a very low FD-factor in the chemically leavened bread. This indicated, that the flour contained only minor amounts of the precursor (s) for the formation of Acp. On the other hand, 2(E),4(E)-decadienal, 2(E),4(E)-nonadienal, l-octen-3-one and 2(Z)-nonenal, which are undoubtedly formed by a heat-induced oxidative degradation of the flour lipids, became predominant odorants in the chemically leavened compared to the yeast-leavened bread. 

CM of 1,9-decadiene with an excess of trialkoxy- and trisiloxy-substituted vinylsilanes results in the formation of , -l,10-bis(silyl)deca-l,9-dienes (Eq.37) [67],... 

Open-chain acetylenes yield pure trans alkenes on reduction with alkali metal in liquid ammonia. However, reduction of cyclodecyne (111) with sodium in liquid ammonia led to a mixture of cis- (112, > 90%) and /rn/w-cyclodecene (113, > 4%y -The formation of the cis isomer (112) was attributed to the reduction of 1,2-cyclo-decadiene (114) formed by a rapid isomerization of the starting cycloalkyne, while the formation of the trans isomer (113) was ascribed to the direct reduction of 111. 

In the presence of diethyl ether the reaction does not proceed beyond the formation of (59). Similar ireatment of 1,6-heptadiene with Et2AlH gives the monoadduct, which requires prolonged heating at 100 °C to cyclize to the cyclohexylmethylaluminum derivatives. In contrast, 1,4-pentadiene, 1,7-octa-diene, 1,8-nonadiene or 1,9-decadiene, show little tendency to cyclize. ... 

Other approaches include the use of difunctional olefins such as 1,7-octadiene, 1,9-decadiene, or para-(3-butenyl)styrene.875 While the former method also generates chain cross-linking (thus unprocessable polymer gels), the latter leads only to LCB formation through hydrogenolysis after a secondary styrene insertion. Tandem Zr/Fe catalysis has been used as well.876 The preparation of iPP with PS branches has been achieved by co-polymerization of propylene with allyl-terminated PS macromonomers.877... 

Fig. 3.33 Formation of 2-pentylpyridine from 2,4-decadienal and ammonia 3.2.3.3.S Taste Compounds...

These results indicate fhat fhe methylidene complex is fhe botUeneck in the ADMET reaction with Grubbs catalysts, which suggests fhat performing fhe ADMET reaction on internal olefins may be beneficial. For example, ADMET wifh 2,10-dodecadiene versus 1,9-decadiene would completely avoid formation of the methylidene and removal of 2-butene would be fhe driving force of the reaction (Scheme 6.28). 

Indeed, one of the most toxic known breakdown products of hpid peroxidation to cells is trans, trans, 2,4, decadienal epoxide (DDE). This product reacts with both dAdo and dGuo, via the formation of a 4,5-epoxy-2(E)-decenal, to yield two highly mutagenic lesions, lN -etheno-2 -dAdo and 1 etheno2-dGuo [54,67,68]. 

An example of these properties is shown in Table 27, in which small amounts of 1,9-decadiene were copolymerized with ethylene with a Cr/ silica catalyst activated at 700 °C. The observed drop in polymer density upon addition of 1,9-decadiene was minor, indicating little SCB formation. Other property changes, however, were extreme. The low shear measurements (MI, melt viscosity at 0.1 and 0 s-1) and the relaxation time increased dramatically, whereas the higher shear measurements... 

In Colombian green coffee, Boosfeld et al. (1994) and Boosfeld and Vitzthum (1995) elucidated the structure of two pairs of unsaturated aldehydes, (E,E)-2,4- and (2F,4Z)-2,4-nonadienal as well as (E,E)-2,4- and (2 , 4Z)-2,4-decadienal, probably generated via autoxidation of unsaturated fatty acids and contributing particularly to the typical green-coffee odor. The products were identified by mass spectrometry, GC-FTIR and NMR spectroscopy. The authors used particularly mild extraction techniques in order to avoid artifact formation and isomerization of the conjugated double bonds. The sensory impressions of these aldehydes at the sniffing port varied from metallic, fried, and flowery to oily notes. 

Brazil nut (Bertholletia excelsa L.) is consumed either raw or roasted as a snack or used in a variety of confectionary products. Brazil nut contains a high amount of fat (65%-70%), which is rich in unsaturated fatty acids [39,40]. The only report on the volatile composition of Brazil nut was published by Clark and Nursten [41]. They compared both high vacuum distillation and Likens and Nickerson steam distillation for the extraction of the volatile compounds, and found the latter technique was more susceptible to artifact formation as evidenced by the presence of the lipid oxidation products 2,4-nonadienal and 2,4-decadienal in that extract. Both extracts were analyzed by gas chromatography-olfactometry (GCO) on both polar (Carbowax 20M) and nonpolar... 

In their studies toward the total synthesis of Taxol , Danishefsky and co-workers have focused their attention on the formation of eight-membered rings by an intramolecular Heck reaction proceeding by an -exo-trig cyclization of a 2-halo-1,8-decadiene system (Scheme 19, Table 14). 

The purely thermal processes that are involved include the formation of cw-9,10-dihydronaphthalene (C9,10) from bullvalene (BV), bicyclo[4.2.2]decatetrene (422) and its intramolecular Diels-Alder adduct, tetracyclo[4.4.0.0 0 ]decadiene (TCD), from lumibullvalene (LBV), isobullvalene (IBV), tricyclo[5.3.0.0 ]deca-3,5,9-triene (TDT), and isolumibullvalene (ILBV), from basketene (BSK), NHC, TRQ, and the syn and anti isomers of tricyclo[4.4.0.0 ]decatriene (S and A, respectively), and from all c/ -cyclodecapentaene (C5), snoutene (SNT), and diademane (DIA). A more recent review includes many heats of formation and enthalpies of activation ... 

Cyclohexaneacetic acid Cyclohexanecarboxylic acid Cyclohexanone Cyclohexyl acetate Cyclohexyl anthranilate Cyclohexyl butyrate Cyclohexyl cinnamate Cyclohexylethyl acetate Cyclohexyl formate Cyclohexyl isovalerate Cyclohexyl propionate Cyclopentanethiol Cyclopentanone p-Cymene trans-trans-2,4-Decadienal... 

Dihydromyrcenol Dihydromyrcenyl acetate Dimethyl benzenebutanol 2,4-Dimethyl-3-cyclohexene carboxaldehyde Dimethylcyclohexyl methyl ketone 4,8-Dimethyl-4,9-decadienal 5,9-Dimethyl-4,8-decadienal Ethyl acetoxyhexanoate Ethyl o-anisate Geranyl butyrate Geranyl formate Geranyl nitrile Greenyl acetate Hexahydrohexamethyl cyclopentabenzopyran Homolinalool Homolinalyl acetate Hydroxycitronellal Hydroxycitronellal dimethyl acetal Hydroxycitronellal methyl anthranilate Hydroxymethylheptyl methyl ketone Isoamyl phenethyl ether Isoamyl salicylate Isobornyl acetate 2-lsobutylquinoline a-Isomethylionone... 

Our recent study on the activity for metathesis revealed a high reactivity of 1,9-decadiene and cyclooctene in their reactions with triethoxy- and trisiloxy-substituted vinylsilanes [20]. When the mixture containing vinylsilane and 1,9-decadiene was heated in the presence of Grubbs catalyst, the formation of mono- and bis(silyl)dienes, accompanied by a polymeric product, was detected. The replacement of 1,9-diene with cyclooctene in the reaction mixture has resulted in the same products. The reactions can be illustrated by Eqs. 6 and 7. l,10-bis(silyl)-substituted dienes were isolated with 50-70 % yields and characterized spectroscopically. In the case of disubstituted products separated by distillation, no double bond migration was observed. The only process observed in that case was E/Z isomerization, so only Z,Z-disubstituted products could be isolated. 

---