Cyclo-oct-2-enone

Cyclohept-2-enone and cyclo-oct-2-enone undergo ring-contraction to 1-acetyl-cyclopentene and 1-acetylcyclohexene, respectively, in aqueous ethanol containing triethylamine at 140 Treatment of eucarvone with sodium hydride and methyl iodide gave a mixture of products including the bicyclic compounds 3-methylcar-4-en-2-one and l,3-dimethylcar-4-en-2-one. Attempts to dehydrate cycloheptene (237) gave mixtures of dimethylisopropylbenzenes. ... 

Cyclo-octa-1,3-diene is obtained by heating 8,8-di-iodobicyclo[5,l,0]octane in quinoline at 155°C. Treatment of l-trimethylsilyloxybicyclo[5,l,0]octane with iron(iii) chloride and sodium acetate gave cis-cyclo-oct-2-enone (92 %). °... 

Direct photoisomerization of cyclo-octene gives a trans. cis ratio of 49 51, respectively, in the photostationary state, whereas photostationary trans cis ratios of 5 95 and 13 87, were observed on toluene photosensitization in the liquid and vapour phases, respectively. On irradiation, mixtures of isoprene and either cis-cyclohept- or cis-cyclo-oct-2-enone give the Diels-Alder adduct of the trans-cyclo-alkene similar Diels-Alder adducts were obtained using cyclopentadiene. ... 

Oxymercuration-demercuration of 5,6-epoxy- and 4,5-epoxy-cyclo-octenes leads largely to CTido-9-oxabicyclo[3.3 l]nonan-2-ol. Cyclo-oct-4-enone and cyclo-oct-2-enone give largely hydroxy-ketones, whereas cyclo-oct-3-enone... 

Cyclic Ketones.—Protonation of cyclohept-2-enone or cyclo-oct-2-enone at low temperature produces two stereoisomers of the form (322) and (323), where n = 1 or 2, respectively. ... 

N.m.r. data for several unsaturated ketones and the corresponding alkenes, saturated ketones, and alkanes, have been analysed in terms of n-electron densities. Included are data for cyclohepta-2,7-dienone, cyclo-octa-2,4-dienone, cyclohept-2-enone, cyclo-oct-2-ene, and tropone. The n.m.r. spectra of several di-esters, including medium-ring examples, have been reported. Boron trifluoride complexa-tion of cycloalkanones has been studied using n.m.r. at low temperatures (— 85 to —125 °C) separate signals for both the complexed ( 24 p.p.m. downfield) and free ketones were observed. ... 

Cyclo-octa-2,4-dien-l-ol is converted into anti -2,3-epoxycyclo-oct-4-enol (91 %) on treatment with m-chloroperoxybenzoic acid, whereas t-butyl peroxide-VO(acac)2 gives the bicyclic ether (163 78 %). 2,6,6-Trimethylcyclohepta-2,4-dienol is converted into syn-2,3-epoxy-2,6,6-trimethylcyclohept-4-enol (65 %) by m-chloroperoxybenzoic acid and into (164 86%) by t-butyl per oxide-VO(acac)2- As the syn-epoxycyclo-heptenol gave (164) on treatment with VO(acac)2, it was suggested that in the t-butyl peroxide-VO(acac)2 epoxidations the bicyclic ethers were formed via the syn-2,3-epoxides and subsequent transannular S 2 substitution. The nature of the products obtained from reactions of epoxides with lithium diethylamide is solvent dependent. Thus the mono-epoxide of cyclo-octa-1,5-diene gives cyclo-oct-3-enone in benzene or ether and bicyclo[5,l,0]oct-2-en-syn-6-ol in HMPT the exocyclic... 

When di-p-chloro- and di-p-methoxidobis(2-methoxycyclo-oct-5-enyI)dipallad-ium(ii) were refluxed in methanol with and without added base, and when dichloro-(cyclo-octa-l,5-diene)palladium(ii) was refluxed in methanol with added base, complex mixtures of products were obtained comprising cyclo-oct-4-enyl methyl ether, cyclo-oct-4-enone, and cyclo-octa-2,4-, -2,5-, -3,5-, and -1,5-dienyl methyl ethers. 

An examination of the phosphorescence spectra and lifetimes of Py-un-saturated ketones, including 2,2-dimethylcyclohept-3-enone and cyclo-oct-3-enone. suggests n-iz triplet excited states. ... 

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