Frans-3-Heptene

Van Ruth et al. (1995) described the flavour components in bell peppers. Out of 47 compounds identified, 12 could be detected by assessors at a sniffing port on a gas chromatograph. 3(2220) 2-Methylpropanal,9 2-methylbutanal, 10 3-methylbutanal, 13(2370) 2,3-butanedione, 15(3382) l-penten-3-one, 19(2557) hexanal, 25(2540) heptanal, 29 P-ocimene, 35 frans-3-hepten-2-one, 39 dimethyltrisulphide, 45(3132) 2-isobutyl-3-methoxypyrazine and 47(3639) P-cyclocitral were the major compounds. 

Both 2-acetoxy-frans-3-heptene and 4-acetoxy-trans-2-heptene were found to give a similar mixture of 1,3-heptadiene and 2.4-heptadiene upon heating at 350-360°C in the gas phase. Examination of recovered starting material revealed it to consist of a mixture of 60% of the 2-acetoxy compound and 40% of the 4-acetoxy compound, no matter which had been the reactant. Rationalize these results. 

Until recently only few examples on asymmetric epoxidation using iron-based catalysts were reported in the literature (Scheme 6) [42-44]. With [Fe(BPMCN) (CF3S03)2] 10, 58% of the epoxide with 12% ee was obtained in the oxidation of frans-2-heptene [42]. 

Olefin styrene, a-methylstyrene, frans-p-methylstyrene, 1-hexene, c/s and frans-4-octene, c-pentene, c-hexene, c-heptene, indene, 1,2-dihydronaphthalene... 

Suggest an efficient synthesis of frans-2-heptene from propyne and any necessary organic or inorganic reagents. J... 

A series of polymer-anchored epoxidation catalysts was obtained by modifying Merrifield resin with imidazole [61], diphosphines [62], or piperazine [63] followed by treatment with UV-activated Mo(CO)6. High activities in the epoxidation of cyclic (cyclooctene, cyclohexene, indene, and a-pinene) as well as linear alkenes (styrene, a-methylstyrene, 1-heptene, 1-dodecene, cis- and frans-stilbene) were observed using TBHP as oxidant. The catalysts were recovered and reused up to 10 times in the epoxidation of cyclooctene without loss of activity. 

The discovery of iron complexes that can catalyze olefin czs-dihydroxylation led Que and coworkers to explore the possibility of developing asymmetric dihydroxylation catalysts. Toward this end, the optically active variants of complexes 11 [(1R,2R)-BPMCN] and 14 [(1S,2S)- and (lP-2P)-6-Me2BPMCN] were synthesized [35]. In the oxidation of frans-2-heptene under conditions of limiting oxidant, 1R,2R-11 was foimd to catalyze the formation of only a minimal amount of diol with a slight enantiomeric excess (ee) of 29%. However, 1P-2P-14 and 1S,2S-14 favored the formation of diol (epoxide/diol = 1 3.5) with ees of 80%. These first examples of iron-catalyzed asymmetric ds-dihydroxylation demonstrate the possibility of developing iron-based asymmetric catalysts that may be used as alternatives to currently used osmium-based chemistry [45]. 

Der stereochemische Verlauf der Brom-Addition ist ebenfalls von den Reaktionsbedin-gungen abhangig. So liefert die radikalische Addition (peroxidisch oder photochemiscb) von Brom an 7-Oxa-bicyclo[2.2.1]hepten-(2)-e ro-5,exo-6-dicaibonsaure-anhydrid sowohl das cis- als auch das frans-Addukt, wabrend unter ionischen Bedingungen nur die trans-... 

Heptenal (No. 1360, frans-2-heptenal) was evaluated by the Committee in 2004. It was concluded that 2-( )-heptenal was not a safety concern at current levels of intake. 

It is believed that a six-membered ring like transition state is involved in this condensation, as shown here. It is predicted that in the presence of an acid, the carbonyl group would be protonated and even polarized to be more electrophilic, thus the condensation is accelerated. As for the steric hindrance, the major product should be in fran -configuration, as in the case of forming tran -S-octen-l-ol exclusively from 1-heptene." ... 

The volatiles derived from oils containing hnolenic acid (soybean and canola oils) have significant sensory impact and lower threshold values than the volatiles derived from oils containing linoleic acid (cottonseed, com and sunflower oils) (Table 5.1). The most sensory-significant linolenate-derived aldehydes (with lower threshold values) were characteristic in having n-3 unsaturation. These trends explain why linolenic acid oils develop undesirable odors and flavors at much lower levels of oxidation (peroxide value of less than 1) than linoleic acid oils (peroxide value of 10). Similarly, potent volatile aldehydes have been identified in fish oil oxidized at very low levels of oxidation by static and dynamic headspace GC (see F.2) and detected by GC-MS at parts per billion levels, including cw-4-heptenal (1250 ppb), fran, cw-2,6-nonadienal (1231 ppb)andCiXcw-3,6-nonadienal(627 ppb). Cis-4-heptenal is produced by decomposition of fran, cw-2,6-nonadienal, which can be produced in turn by the decomposition of n-7 and n-9 hydroperoxides derived from the oxidation of 20 4, 20 5 and 22 6 n-3 PUFA (Chapter 4, D4). 

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