Hept-l-ene

Hept-l-ene [592-76-7] M 98.2, b 93 /771mm, d 0.698, n 1.400. Distd from sodium, then carefully fractionally distd using an 18-in gauze-packed column. Can be purified by azeotropic distn with EtOH. Contained the 2- and 3-isomers as impurities. These can be removed by gas chromatography using a Carbowax column at 70°. 

The geometry of bicyclic rings can also cause distortion of the alkene bond from coplanarity. An example is bicyclo[2.2.1]hept-l-ene ... 

For carbenes 25 and 26 1,2-shifts of bonds a and b will lead to different bridgehead olefins, 17 and 27 for 26, and 1-norbomene 16 and bicy-clo[3.1.1]hept-l-ene (30) for 25, whereas carbene 24a will only give alkene 15. In accordance with experimental observations,19 calculations show that the more strained bond will migrate preferentially. 

The paper devoted to the phosphetan synthesis26 describes optimum conditions for the cyclization process leading to (22), and explains the effects of other conditions in terms of competing reactions, such as alkene polymerization or addition of hydrogen chloride. Assignment of structure (23) to the product from hept-l-ene (24)... 

The unconsumed reactants and products were both easily removed from the reaction mixture by extraction with K-hexane, which is not miscible with [BMIMJPFg. The brown-red ionic liquid phase containing the catalyst was reused five times with PhI(OAc)2 as the oxidant. The recovered catalyst gave catalytic activity comparable to that of the original. In epoxidation of styrene and of cyclohexene, both catalytic activity and selectivity fell slightly after five reuses. In the conversion of hept-l-ene, the reused catalyst showed the same activity and selectivity as the fresh catalyst, and the catalyst was shown to be unchanged after the reaction. 

Whereas oxidation leaves the fused thietane derivative 218 intact by giving the corresponding sulfone, reduction produces the 4-isopropyl-l,l-diphenyl-bicyclo[4.1.0]hept-l-ene (219) by extrusion of sulfur (Eq. 58). The general oxidation procedure to convert thietanes to their sulfones comprises refluxing with peracetic acid. 

Cyclopropenes possess appreciable high reactivity toward carbomagnesiation . For example, dialkylmagnesium compounds react with spiro[2.4]hept-l-ene (75) to give the carbometalated products 76 (Scheme 53) . The iyw-addition has been confirmed by D2O quenching of the reaction. 

Carbenes are known intermediates in the thermolytic or photolytic decomposition of the lithium or sodium salts of tosylhydrazones, which, for endocyclic carbenes, results in ring contraction when the elimination of / - or y-hydrogens is impeded. Simple cyclobutanes generally cannot be prepared by this route from monocyclic cyclopentanone tosylhydrazones. However, the lithium salt of bicyclo[2.2.1]heptan-7-one tosylhydrazone gave bicyclo[3.2.0]hept-l-ene (4) as the major product (74%) by vacuum pyrolysis at 185 JC/20 Torr, together with bicyclo[2.2.1]heptane (14%) and tricyclo[2.2.1.02,7]heptane (12%) in 80% overall yield.67... 

Analogously, the thermolysis of the 1-methyl derivative in bis(2-methoxyethyl) ether (diglyme) at 160 °C for 30 minutes gave 2-methyIbicyclo[3.2.0]hept-l-ene (5) with 82% selectivity in 12% overall yield, while flash-vacuum pyrolysis (250°C/1 x lO -lO 3 Torr) gave 5 with 75% selectivity and 47-68% overall yield of volatile products.68... 

Reaction of 7-acetoxy-2,6,6-trimethylbicyclo[3.2.0]hept-l-ene with atmospheric oxygen gave the rearranged alcohol 7-acetoxy-2,6,6-trimethylbicyclo[3.2.0]hept-2-en-1-ol (3).57... 

Spectra from hept-l-ene, hept-2-ene, and hept-3-ene have also been obtained by Shopov et al. (161, 162) on Ni/Si02. 

What about the case in which the double bond contains one carbon on a 0-length bridge Such species are often considered as violating Bredt s rule. We can make but one thermochemically meaningful comparison of such a species with any other olefin that has the same alicyclic framework but lacks this Bredt-violating, strain-increasing feature. This is for bicyclo[3.2.0]hept-l-ene (23a) in comparison to its isomers, the -2- and -6-ene (23b and 23c) 23a is 49 and 28 kJ mol 1 less stable than 23b and 23c, respectively. 

Directed coupling reactions, where no cross-coupling may occur, requires the reagents derived from the appropriate synthons to be ionically different at the reactive site. The carbon-carbon coupling reaction to form hept-l-ene (Expt 5.8), illustrates the importance of selecting the reactive, and readily available, allyl bromide (cationic site) with butylmagnesium bromide (anionic site) (A), rather than the other alternative (B). 

Reaction of dialkylmagnesiums with spiro[2,4]hept-l-ene proceeds with second order kinetics and leads to the cw-2-alkyl cyclopropyl magnesium alkyl with a-sub-stituent effects on the rate in the order primary < secondary > tertiary, suggesting a balance between competing electronic and steric effects 199). 

Cp2HfHCl] Hept-l-ene /r[Pg.682]

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