Octa-l,7-diene

Experimental Procedure 3.2.6. Alkylidenation of a Ketone 4-Methyl-l-phenyl-octa-l,3-diene... 

With tricarbonyl(cyclo-octa-l,3-diene)iron, C2F4 gives a compound similar to [70] as major product, together with [72] in which the C2F4... 

Pyrolysis of 1,2-dimethyltetramethoxydisilane at 350 ""C gave methoxymethyl-silane which reacts with cis,cis-cyclo-octa-l,3-diene to give the silacyclopropane (173) which rearranges under the reaction conditions to give 1-methoxy-1-methyl-1-silacyclonona-2,8-diene by a free-radical cleavage of the C-1—C-8 bond and trans-annular hydrogen transfer. ... 

Irradiation of 2,3-benzo-6,6-dimethylcydohepta-2,4-dienone gave a mixture of two dimers, (208) and its isomer with the opposite configurations at C-1 and C-9. These may have been formed by a photochemical [ 4s + 2a] cycloaddition, followed by a 1,3-acyl shift.Irradiation of cyclo-octa-2-en-l,4-dione gave the dimer (209), whereas irradiation in the presence of cyclopentadiene or furan gave the [4 + 2] adducts (210 X = O or CH2), and irradiation in methanol gave the methanol adduct, 2-methoxycyclo-octa-l,4-dione. The photochemical cycloadditions of cyclohex-enone to cycloheptatriene, cycIo-octa-l,3-diene, and cyclo-octa-1,5-diene, and of cyclopentenone to cyclo-octa-1,3-diene, have been studied. ... 

Treatment of 5,8-bis(trimethylsilyl)cyclo-octa-l,3,6-triene or 3,5,8-tris(trimethyl-silyl)cyclo-octa-l,3,6-triene with triruthenium dodecacarbonyl gave the pentalene complexes (352 X = H or SiMe ). Tricarbonyl(Ti-cyclo-octa-l,5-diene)ruthenium and tricarbonyl(T)-cyclo-octa-l,3-diene)osmium have been prepared. They react with trityl fluoroborate to give cyclo-octadienylium complexes [(CgHn)M(CO)3] which react with anionic nucleophiles to give neutral compounds, some of which... 

The reaction of bis(cyclo-octa-l,3-diene)nickel with hexafluorobut-2-yne gives (cyclo-octadiene)nickel[(hexakistrifluoromethyl)benzene], (114) or (115), which decomposes slowly at room temperature. Other ligands can displace the cyclo-octadiene, and alternative routes to some of the compounds are also reported, including the novel displacement of ethylene from (Ph3P)2Ni(C2H4) by preformed hexakis(trifluoromethyl)benzene. The compounds are formulated either as formally five-co-ordinate nickel complexes, with the planar arene occupying three co-ordination positions and free... 

In cyclohepta-l,3-diene, which has C, symmetry, all the carbon atoms except the one remotest from the double bonds are coplanar, giving the molecule a partly open envelope configuration (20), with flap angle a = 73 out-of-plane. Butadiene-like coi jugation is observed. Like cyclohexa-1,3-diene, cyclo-octa-l,3-diene has its strain relieved by a twist (here 38°) about the =C-C= bond, but the molecule appears to possess no elements of symmetry. Formula (21) shows a projection down the =C-C= bond. 

Base and Substituted Halogenomethane Method. As well as a correction to the literature of last year concerning cycloaddition of 1,2,2-trimethylpropylidene-carbene, there have been reports of routine dihalogenocarbene additions to 1,1-dicyclopropylethylene, cyclo-octa-l,3-diene, bullvalene, vinyl ethers, 1-ethoxybuta-1,3-dienes, and tricyclo[4,4,l,0 ]undeca-3,8-di-... 

Substituted derivatives of groups (1) and (2) above, e.g. 3-methylcyclo-butene and 1-methylcyclo-octa-l,5-diene. 

Scheme 6.30 Structure ofthe trapping products of bicyclo[3.2.1]-octa-2,3-diene (123) with 1,3-cyclopentadiene, (Z)-l, 3-pentadiene and 2,3-dimethyl-l, 3-butadiene and ofthe dimers of123.

Scheme 6.69 Generation of 4-methoxybenzyl (6R,7S)-8-oxo-7-(phenylacetamido)-l-azabicyclo[4.2.0]octa-2,3-diene-2-carboxylate (323) from the carbacephalosporin triflate 322 and the interception of323 by indene and (Z)-/ -deuterostyrene.

Comparison with the reported reactivity of the spiro[2.5]octa-l,4-dien-3-one 110 and 4-(hexafluoroisopropylidene)cyclohexa-2,4-dien-l-one 111 have suggested that the conjugated cyclopropane ring of compounds 108 and 109 imparts a strong acid dependence to its reactivity with nucleophiles, Eq. (45). This property is likely to be relevant for the exceptional reactivity of these antibiotics toward DNA [148]. 

Mechanistic studies of the equilibrium between cycloocta-1,5-diene (36) and 1,2-divinylcy-clobutancs (37)Vfi and between 2,3-dimethylenebicyclo[2.2.0]hexane (38) and bicy-clo[4.2.0]octa-l,5-diene (39)77 show the intermediacy of diradicals in these rearrangements. 

At 150 °C, the analogous 2-methylenetricyclo[4.1.0.01,3]heptane (34) equilibrated with 35 and 36 as products of a methylenecyclopropane rearrangement and a subsequent retro-Diels Alder reaction, respectively, until at 180 °C an irreversible rearrangement to bicyclo[4.2.0]octa-l,5-diene and 3,4-dimethylenehexa-l,5-diene (39) via diradical 37 took place.223,224 Increasing pressure favored the formation of the bicyclic system 38 (50% yield at lOOTorr).223... 

Vanhaelen, M., Vanhaelen, F. R. and Geeraerts, J. (1980). Occurrence in mushroom (Homobasidiomycetes) of d.v-ocla-1,5-dicn-3-ol and /nms-octa-l,5-dien-3-ol, attractant to the cheese mite Tyrophagus putrescentiae (Schrank) (Acarina, Acaridae). Experientia 36 406 107. 

Another type of bicyclo[3.3.0]octadienone formation is observed in the reactions of 4,4-gem-disubstituted 1,6-heptadiynes (353) with HSiMe2Bu-t catalyzed by Rh(acac)(CO)2 or Rh2Co2(CO)i2 under forced conditions, i.e. at 120 °C and 50 atm of CO, affording 7,7-disubstituted bicyclo[3.3.0]octa-l,5-dien-3-ones (354) in 71-95% isolated yields (equation 143)340,341. 

An alternative procedure is to convert the carbonyl compound into the toluene-p-sulphonylhydrazone,12 followed by reduction with either sodium borohydride in acetic acid,13 or with catecholborane, followed by decomposition of the intermediate with sodium acetate or tetrabutylammonium acetate.14 The former method is illustrated by the conversion of undecan-6-one into undecane (Expt 5.6), and the latter by the conversion of acetophenone into ethylbenzene (Expt 6.4, Method B). A feature of these methods is that with a, / -unsaturated ketones, migration of the carbon-carbon multiple bond occurs thus the tosylhydrazone of isophorone gives 3,3,5-trimethylcyclohex-l-ene, and the tosylhydrazone of oct-3-yn-2-one gives octa-2,3-diene. 

Using a relative rate method, rate constants for the gas-phase reactions of O3 with 1- and 3-methylcyclopentene, 1-, 3- and 4-methylcyclohexene, 1-methylcycloheptene, cw-cyclooctene, 1- and 3-methylcyclooctene, cycloocta-1,3- and 1,5-diene, and cyclo-octa-l,3,5,7-tetraene have been measured at 296 2 K and atmospheric pressure. The rate constants obtained (in units of 10-18 cm3 molecule-1 s-1) are as follows 1-methylcyclopentene, 832 24 3-methylcyclopentene, 334 12 1-methylcyclohex-ene, 146 10 3-methylcyclohexene, 55.3 2.6 4-methylcyclohexene, 73.1 3.6 1-methylcycloheptene, 930 24 d.s-cyclooclcnc, 386 23 1-methylcyclooctene, 1420 100 3-methylcyclooctene, 139 9 d.v.d.v-cycloocta-1,3-diene, 20.0 1.4 cycloocta- 1,5-diene, 152 10 and cycloocta-l,3,5,7-tetraene, 2.60 0.19 the indicated errors are two least-squares standard deviations and do not include the uncertainties in the rate constants for the reference alkenes (propene, but-l-ene, d.s-but-2-ene, trans-but-2-ene, 2-methylbut-2-ene, and terpinolene). These rate data were compared with the few available literature data, and the effects of methyl substitution have been discussed.50... 

Direkte UV-Bestrahlung wandelt Cycloocta-l,3,5-trien (Formel 121) hauptsachlich in Bicyclo[4,2,0]octa-2,7-dien (Formel 122) und Tricyclo-[3,2,l,0a-8]oct-3-en (Formel 123) (58,222,340) um. Daneben werden noch all-trans-Octatetra-l,3,5,7-en (222) und Cyclo-octa-l,5-dien (58) nach-gewiesen. 

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