Trans- 1,6-octadiene

COOC C00CH 3 Aceton trans,trans-Octadien-(2,6)-disaure-dimeihylester + cis,trans.. + cis,cis-.. . 3... 

Martin and Eisenmann have re-investigated the thermolysis of syn- and anti-tricyclo[4,2,0,0 ]octane (511) and (512). Both ultimately give cis,cis-cyclo-octa-l,5-diene but the re-investigation shows that cis,trans-octa-l,5-diene is also produced and that it isomerizes to the all-cis-diene under the reaction conditions. The cis,trans-diene was trapped with hexachlorocyclopentadiene, and was also characterized as its dimer or its silver nitrate complex. Both (511) and (512) give mixtures of cis,cis-and cis,trans-octadiene in a co. 3 5 ratio. Thus the single-inversion pathway usually found in the pyrolysis of bicyclo [2,2,0] hexanes is also followed, at least partially, by... 

In more recent extensive studies by BRPRA/NRPRA/MRPRA teams 2-methyl pent-2-ene and trans-2,6-dimethyl octa-2,6-diene (dihydromyrcene) have been preferred for studying inter- and inter-l-intra-chain reactions respectively. (The choice of the trans-octadiene rather than the more pertinent els- isomer is a consequence of the... 

Figure 13.37 shows the UV spectrum of the conjugated diene cis,trans-, 3-cyc o-octadiene, measured in ethanol as the solvent. As is typical of most UV spectra, the absorption is rather broad and is often spoken of as a band rather than a peak. The wavelength at an absorption maximum is refened to as the X ax of the band. There is only one band in the UV spectrum of 1,3-cyclooctadiene its X ax is 230 ran. In addition to UV-VIS bands are characterized by their- absorbance (A), which is a measure of how much of the radiation that passes through the sfflnple is absorbed. To correct for concentration and path length effects, absorbance is converted to molar absorptivity (e) by dividing it by the concentration c in moles per liter and the path length I in centimeters. 

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol. ... 

Bei der Hydroaluminierung von Alkinen tritt die Oligomerisierung oft bereits bei nied-rigeren Temperaturen in den Vordergrund. So erhalt man z.B. aus 3,3-Dimethyl-l-phe-nyl-butin (I) und Bis-[2-methyl-propyl]-aluminiumhydrid (1 1) bei 50° 94% d.Th. cis-3,3-Dimethyl-l-phenyl-buten-(l) (II)5 neben 6% d.Th. trans,trans-2,2,7,7-Tetramethyl-4,5-diphenyl-octadien-(3,5) (III) ... 

The plant is strongly aromatic on account of an essential oil which comprises cis-a-ocimene (25.11%), 3,7-dimethyl-l,6-octadien-3 ol (16.85%), and trans-nerolidol (13.89%), hence the use of the plant in aromatherapy. A methanolic extract of bark of Litsea cubeba (Lour.) Pers. and its fractions (0.01 mg/mL) from bark inhibit NO and PGE2 production in LPS-activated RAW 264.7 macrophages without significant cytotoxicity at less than 0.01 mg/mL concentration. The methanol extract decreased the enzymatic activity of myeloperoxidase (0.05 mg/mL). These findings suggest that L. cubeba is beneficial for inflammatory conditions and may contain compound(s) with anti-inflammatory properties (63). Can we expect the vasorelaxant laurotetanine (64) isolated from the plant to exert such activity ... 

A common example of Cope rearrangement involving [3, 3] sigmatropic rearrangement in a 1, 5 diene is the pyrolysis of meso 3, 4 dimethyl hexa-1, 5 diene giving exclusively cis, trans isomer of 2, 6 octadiene. The process involves a six electron transition state which has a chair like configuration and substituents occupy equatorial sites. 

Pericas and coworkers173 studied the endo selective reactions of 1-alkoxy-l,3-butadienes and 1-alkoxy-l,3-octadienes with maleic anhydride. They found that the trans-2-phenyl-cyclohexan-l-ol and 3-exo-(neopentyloxy)isobornan-l-ol based chiral dienes induced the highest facial selectivities. The relative transition state energies for the formation of the different diastereomers were calculated using semi-empirical methods (AMI). 

Oxidation of 1,5-dienes to c -tetiahydrofurandiols was accomplished with RuO /aq. Na(10 )/acetone-EtOAc thus 2,5-dimethyl-1,5-hexadiene gave tetrahydrofurandiol, geranyl acetate yielded cw-tetrahydrofurandiol, and trans, tra 5-2,6-dimethyl-2,6-octadiene-l,8-diol diacetate (1) gave tetrahydrofuran ketol diacetate (2) (Fig. 3.12 cf. mech. Ch. 1) [174],... 

Auch durch Retro-Diels-Alder-Reaktion konnen Azoalkane erhalten werden. Die ther-mische Zersetzung von 1,2,3,6-Tetrahydro-pyridazin liefert vorzugsweise cis-Dimethyl-di-azen, wahrend das 2,3-Dimethyl- uberwiegend in trans-Dimethyl-diazen zerfallt. Zur stereochemischen Begriindung hierfiir s.Lit.3. 

V 1,3-Octadien A1(C2Hj)3 -t- VCI3 in n-Heptan 87 trans-isotaktisch 4,85 (73)... 

In the same year the biotransformation of these monoterpenes by B. cinerea in model solutions was described by another group [41]. Although the major metabolites found were co-hydroxylation compounds, it is important to note that these authors only identified the -isomers in the extracts and that some new compounds were detected that were not described by the previous group, Fig. (9). Geraniol (20) was mainly transformed to (2 ,5 )-3,7-dimethyl-2,5-octadiene-l,7-diol (53), ( )-3,7-dimethyl-2,7-octadiene-l,6-diol (54) and (2 ,6 )-2,6-dimethyl-2,6-octadiene-1,8-diol (43), nerol (14) to (2Z,5 )-3,7-dimethyl-2,5-octadiene-1,7-diol (55), (Z)-3,7-dimethyl-2,7-octadiene-l,6-diol (56), and (2E,6Z) 2,6-dimethyl-2,6-octadiene-1,8-diol (47). Furthermore a cyclisation product (57) was formed which was not previously described. Finally citronellol (4) was converted to trans- (60) and cw-rose oxide (61) (a cyclisation product not identified by the other group), ( )-3,7-dimethyl-5-octene-l,7-diol (58), 3,7-dimethyl-7-octene-l,6-diol (59) and ( )-2,6-dimethyl-2-octene-1,8-diol (34). 

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. 

Potassium acetate (acetic acid, MeOH) Butadiene trans-3-Hexene (11-26%), 1-pentene 257,258) 3-methyl-1-pentene, CjQ-dienes (12-58%), 3,7-decadiene, 3-ethyl-l,5-octadiene ... 

Butadiene trans, frans- 1,8-Dime thoxy-2,6-octadie tie (13%), Irani-l,6-dimethoxy-2,7-octadiene (13%), 3,6-di-methoxy-l,7-octadiene (13%), dimethoxydodeca- ... 

The reaction of butadiene with methanol leads to the formation of the telomers l-methoxy-2,7-octadiene (trans- and cis-), 3-methoxy-l,7-octadiene and the dimers 1,3,7-octatriene and 4-vinylcyclohexene (as minor products). Using palladium(II) acetate with either PPh3 or TPPMS in a biphasic system with ionic liquid leads to an inactive system when [C2mim]+ and [C4mim]+... 

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