4-Hydroxy-2,3-octenal

Oxo-4-[6-carboxy-hexen-(2)-yl]-3-[3-hydroxy-octen-(l)-yl]- 723 3-Oxo-2,4-dimethyl- 622 3-Oxo-1,5-diphenyl- 669... 

Fig. 5.6. HPLC of reference aldehydes. Reversed-phase column, Lichrosorb 5RP-18 (9.6 mm x 20 cm) 50°C mobile phase acetonitrile/water (1 1, v/v) flow rate 0.92 ml/ min 222 nm detection. Cs = hydroxypentenal C7 = hydroxyheptenal Cg = hydroxy-octenal G, = hydroxynonenal. (Esterbauer, 1982.)...

Hydrcixy-3-methyl-2-phenyl- 800 2-Oxo-ef do-(bzw. -exo)-4-(3-methoxycarbonyl-propylKsj.7t-7-[3-hydroxy-octen-(l)-yl]- 935... 

Out first example is 2-hydroxy-2-methyl-3-octanone. 3-Octanone can be purchased, but it would be difficult to differentiate the two activated methylene groups in alkylation and oxidation reactions. Usual syntheses of acyloins are based upon addition of terminal alkynes to ketones (disconnection 1 see p. 52). For syntheses of unsymmetrical 1,2-difunctional compounds it is often advisable to look also for reactive starting materials, which do already contain the right substitution pattern. In the present case it turns out that 3-hydroxy-3-methyl-2-butanone is an inexpensive commercial product. This molecule dictates disconnection 3. Another practical synthesis starts with acetone cyanohydrin and pentylmagnesium bromide (disconnection 2). Many 1,2-difunctional compounds are accessible via oxidation of C—C multiple bonds. In this case the target molecule may be obtained by simple permanganate oxidation of 2-methyl-2-octene, which may be synthesized by Wittig reaction (disconnection 1). 

Biochemisch werden Aldehyde i. a. zu den entsprechenden Alkoholen reduziert, wobei sie gelegentlich der mikrobiologischen Cannizzaro-Disproportionierung zu Carbonsaure und Alkohol unterliegen konnen [z. B. 3,7-Dimethyl-octen-(6)-al (Citronellal) zu 8-Hydroxy -2,6-dimethyl-octen-(2) und 3,7-Dimethyl-octen-(6)-sdure]1. 

Hydroxy-3,7-dimethyl-ocladien- 8-Hydroxy-2,6-dimethyl-octen-(2)... 

CN 5-[Hexahydro-5-hydroxy-4-(3-hydroxy-4-methyl-l-octen-6-ynyl)-2(l//)-pentalenylidene]pentanoic acid... 

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

Another unusual structure was identified from cereal leaf beetles, Oulema melanopus ( )-8-hydroxy-6-methyl-6-octen-3-one 199 was found to be a male-specific volatile. Electrophysiological investigations showed a sensitive detection of 199 by both sexes which is consistent with a male-produced aggregation pheromone [367]. The behaviour mediating capacity of the compound needs to be proven. 

However, morpholine-4-carboxylic acid 2-hydroxy-1-methyl-ethyl ester is formed by the reaction of PC and the substrate morpholine in an undesired side reaction. By use of 1.4-dioxane or the pyrrolidones as mediator s3 about 30 to 45% of the morphoUne is consumed by this side reaction. The by-product is contained in the PC phase and can not be extracted to the non-polar product phase. The selectivity to the desired amines is lowered, because of the consiunption of the morphoUne. Thus, PC has to be substituted by another polar solvent (e.g. water, methanol or ethylene glycol) in future experiments. The lactates react with the morphoUne, too resulting in the corresponding amide. Overall, the hydroaminomethylation in the TMS systems PC/dodecane/lactate results in a conversion of 1-octene of about 80%, but in selectivities to the amines of only 50 to 60%. 

Ubcrraschenderweise hat die Elektrophilic des Kondensationsmittels einen entscheidenden EinfluB auf den Reaktionsverlauf bei der Cyclisierung von 2-Acetylamino-3-(bis-[2-hydroxy-ethyl]-amino)-naphthalin. Wahrend mit konz. Bromwasserstoffsaure oder Thionylchlorid das l,4-Diaza-bicyclo[2.2.2]octen-System III cntsteht, bildel sich mit Phosphorylchlorid unter Entalkylierung ein Naphtho[2,3 d]imidazol II88. 

Compared to the anodic oxidation of Z-4-octene-l,8-diol (80%, Table 8) its oxidation with pyridinium dichromate in dimethyl formamide gave as the best chemical alternative only 65 % diacid Nickel peroxide oxidation under mild conditions (1.3 eq. peroxide, 25 °C, 1 M NaOH) led to 45% hydroxy acid 75, whereas under more vigorous conditions (3 eq. peroxide, 80 °C, 1 M NaOH) maleic acid was formed ... 

The epoxidation of dehydrolinalyl acetate 35 provides the corresponding epoxide 36 (75 %) which can lead to karahanaenone 38, a key odorous component of hop oil621. The epoxide 36 can be converted to the keto acetate 37 (82%) by an electrogenerated acid (EG Acid)-catalyzed rearrangement. Hydrogenation followed by alkaline hydrolysis of 37 gives 6-hydroxy-2,6-dimethyl-7-octen-3-one (86%) and subsequent thermal dehydration at 200 °C affords 38 (Scheme 3-12). 

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