Cis-3-Hepten-2-one

Industrial synthesis of nerolidol starts with linalool, which is converted into ger-anylacetone by using diketene, ethyl acetoacetate, or isopropenyl methyl ether, analogous to the synthesis of 6-methyl-5-hepten-2-one from 2-methyl-3-buten-2-ol. Addition of acetylene and partial hydrogenation of the resultant dehydroner-olidol produces a mixture of cis- and trans-nerolidol racemates. 

Methyl-5-hepten-2-one is a valuable precursor for microbial epoxidations and hence the production of chiral ethers with high optical purities. The biotransformation of 6-methyl-5-hepten-2-one (33) by Botryodiplodia malorum CBS 13450 to (/ )-sulcatol (84) was described [61], which is then epoxidised to the (55)-epoxide (85) and opened intramolecularly to cis-(2R,5R)-2-(2 -hydroxyisopropyl)-5-methyltetra-hydrofuran (86) and c/s-(35,67 )-3-hydroxy-2,2,6-trimethyltetrahydropyran (87). Reduction of 6-methyl-5-hepten-2-one (33) with baker s yeast to (5)-sulcatol (88) which was used as substrate for Kloeckera corticis... 

Maleic anhydride Vinylene carbonate, 2.3-Dihydrofuran, 1-Cyclopenten-3-one Endo-cis-bicyclo[2.2.1] -5-heptene-2.3-dicarboxylic anhydride Citraconic anhydride Cyclobutene-3.4-di-carboxylic anhydride ArCr(CO)3 12) CpMn(CO)3 225) Fe(CO)5 3oo.39 ) CpMn(CO)3 225) ArCr(CO)3 12) CpMn(CO)3 15.225) ArCr(CO)3 12) Fe(CO)5 202,285)... 

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-... 

Cl4H2iClOe, Methyl (5S)-4-chloro-3,4-didesoxy-1,2 6,7-di-O-isopro-pylidene-a-D-erythro 3-hepten-5-uio-(1,5)-pyrannoside, 46B, 322 Cl4H21NO5, 4-Carboxy-l,2,4,8 tetramethyl-3,9-dioxatricyclo-[5.2.1.0 ]decane-8-carboxamide, 43B, 399 C14H2 2O2 f cis-8-t-Butyl-3-methylene-l-oxaspiro[4.5]decan-2-one, 44B, 293... 

Analysis of the vacuum volatile constituents of fresh tomatoes was carried out using capillary GLC-MS and packed column GLC separation with Infrared, NMR and CI-MS analysis. Evidence was obtained for the presence of the unusual components 3-damascenone, 1-nltro-2--phenylethane, 1-nltro-3-methylbutane, 3-cyclocltral and epoxy-3-1onone. A method for the quantitative analysis of the volatile aroma components In fresh tomato has been Improved and applied to fresh tomato samples. The quantitative data obtained have been combined with odor threshold data to calculate odor unit values (ratio of concentration / threshold) for 30 major tomato components. These calculations Indicate that the major contributors to fresh tomato aroma Include (Z)-3-hexenal, 3-lonone, hexanal, 3-damascenone, 1-penten-3-one, 3-methylbutanal, (E)-2-hexenal, 2-lso-butylthlazole, 1-nltrophenylethane and (E)-2-heptenal. 

Of course, the symmetry rule specifies which of the two possible courses is favored without excluding the other one the alternative can be favored by other factors which the simple HMO theory does not take into account. For example, cis 1,2,3,4-tetramethylcydobut-l-ene con-rotatorily transforms into cis-trans tetramethylbutadiene when heated at 200 °C. But in dimethylbicydo[3.2.0]-heptene the presence of the five-membered ring makes the conrotatory process impossible, and the opening reaction to 3-dimethyl-cycloheptadiene occurs at 400 °C, probably via a disrotatory process. 

In most cases, the thermal ene reaction is thought to proceed by a concerted mechanism with a cyclic transition state, although this may be unsymmetrical, with one of the new ct bonds more highly developed than the other. The ene reaction often leads to predominantly the endo adduct (in which there is greater overlap of the two components). Thus, different major diastereomers are formed in the reaction of maleic anhydride with fi-2-butene and Z-2-butene, both of which arise from a preference for the endo transition state. Further evidence for the concerted nature of the reaction comes from the observation that the new C—C and C—H bonds are formed cis to each other. The cis addition is exemplified in the reaction of 1-heptene with dimethyl acetylenedicarboxylate to give the adduct 237 (3.152). In this reaction the adduct is formed with the two ester groups on the same side of the alkene such that the hydrogen atom and the allyl residue add to the same side of the triple bond of the enophile. 

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