Cyclo-heptatriene

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

Tropidine CgHj3N —Tropilidene C,Hg (S-cyclo Heptatriene) Anhydroecgonine C9H13O2N —> -eycloHeptatrienccaTboxylic acid CjHgOj... 

The 18-electron rule is especially useful when considering complexes containing ligands such as cyclo-heptatriene, C7H8, abbreviated as cht. This ligand, which has the following structure, can bond to metals in more than one way because each double bond can function by donating two electrons ... 

This degenerate rearrangement has not been observed with 5-dia-zomethyl-l,4-diphenyl-l,2,3-triazole. The diazo function decomposes and the carbene formed reacts, when benzene is used as solvent, into a cyclo-heptatriene. The requirement to have the ester function present at C-4 apparently has to do with stabilization of the diazo function. 

Oberraschende praparative Moglichkeiten eroffneten die Solvolysen von 1,4-Dihydrobenzyl-tosylaten (65), die verschieden substituierbare Cyclo-heptatriene (66) liefem (111). 

FjC-SOjH/FjC-COOH 0-5°, tOmin J-Amino-6,7-dihydro-5H- 80 5... 

More recently, photochemical reactions of 138 with cyclic and acyclic olefins have been described. When 138 is irradiated (Pyrex) with cyclo-heptatriene, [4 + 4]- and [4 + 6]-adducts (247-250, Scheme 16) are obtained in addition, photodimer 242 and o-dibenzoylbenzene (140) were isolated. The ratio of the [4 + 6]-adducts to the [4 + 4]-adducts [(249 + 250)/(247 + 248)] is increased in air-saturated benzene solutions compared with oxygen-free benzene solutions, and enhanced in heavy atom solvents (e.g., chloroform compared with cyclohexane) furthermore, this ratio is decreased in the presence of the triplet quencher azulene. These observations suggest that [4 + 6]- and [4 + 4]-adducts are formed by different mechanisms. 

Cuprous cyclopropylacetylide, prepared from Cul and cyclopropylacetylene in ammo niacal solution couples with 4-iodonitrobenzene in pyridine, yielding 4-nitrophenyl cyclopropylacetylene (equation 154)234. Reaction of the acetylide with tropylium tetra-fluoroborate in acetonitrile, in the presence of LiBr, affords 7-(cyclopropylethynyl)cyclo-heptatriene. The anion radicals obtained by reduction of these compounds were utilized for ESR spectroscopic analysis of the cyclopropyl P hyperfine splittings. 

The study above has some applications. Normally, the equilibrium between cyclo-heptatriene (51, R = H) and norcaradiene (52, R = H) is strongly displaced in favor of the cycloheptatriene. To favor the norcaradiene, the electrocyclic ring opening must be inhibited by strengthening the 1-6 bond. Our analysis shows that this may be achieved by incorporating acceptor groups R. Donor R groups shift the equilibrium to the left.82... 

Troe and his co-workers [27] have recently measured directly the lifetimes of excited molecules undergoing unimolecular decomposition, under essentially collision-free conditions. In these experiments, cyclo-heptatriene, 7-methylcycloheptatriene, 7,7-dimethylcycloheptatriene and 7-ethylcycloheptatriene were each excited electronically with a short pulse of laser radiation. This is followed by a rapid internal conversion to generate highly vibrationally excited, electronic ground state molecules which absorb in the ultraviolet, at longer wavelengths than the unexcited parent. Their decay (isomerisation to alkylbenzenes) was monitored directly with a continuous background source. 

Beispiele sind in der carbocyclischen Reihe etwa das 7-Cyano-7-trifluor-methylcycloheptatrien 36 58> und 7.7-Dicarbomethoxy-cyclo-heptatrien 37 58a,59). 

P. L. Timms, and T. W. Turney, Reactions of Transition-metal Vapours with Cyclo-heptatriene and Cyclooctatetraene, J. Chem. Soc., Dalton Trans. 1976, 2021-2025. 

The cycloaddition of 4-methyl-3//-l,2,4-triazole-3,5(4/f)-dione to spiro[fluorenyl-l,3,5-cyclo-heptatriene] at — 10°C gives the norcaradiene-type cycloadduct, monitored by NMR spectroscopy, which by warming at room temperature is converted to an isomeric triazolidinedione, whose structure is confirmed by X-ray analysis22. 

Pauson et al. (466) have also prepared the ewdo-1-substituted (cyclo-heptatriene)tricarbonylchromium (24) by reaction of Cr(CO)8 or Cr(CO)3(Py)3 with the olefins in the presence of BF3. 

The reaction of diphenylketene with ethoxyacetylene gives a cyclo-heptatriene derivative which reacts in turn with Cr(CO)g to aiford dark red needles of composition (Ci8Hig02)Cr(C0)3 (44, 45). The proposed structure (25) has been confirmed by X-ray analysis (S7) which shows the carbon atom of the triene ring and the chromium atom on opposite... 

Radlick describes a short, if low-yield, preparation of tropone from 1,3,5-cyclo-heptatriene (Shell Chem. Corp.) by oxidation with selenium dioxide in buffered aqueous dioxane the function of the buffer is not known, but it raises the yield by a factor of about two. 

The direct synthesis of benzocyclopropene (1) from benzyne and a carbene or from synthetic equivalents thereof has not yet been realized, but arc-generated carbon reacted with benzene at — 196°C to give benzocyclopropene (1) in 11% yield, together with toluene (24%), cyclo-heptatriene (17%), 7-phenylcycloheptatriene (21%) and heptafulvene (17%). Phenylcarbene in an excited state is a possible intermediate in the formation of benzocyclopropene. ... 

A 1,6-cycloaddition was wrongly claimed to occur with benzyne and cyclo-heptatriene. The structure of the cycloadduct is reliably established as 25, and the isomer 26 derived from an ene reaction was also obtained.32 1,8-Cycloaddition of benzyne occurs with 8-cyanoheptafulvene (27) to give 28.3 3 It is clearly possible to envisage similar reactions occurring with heterocyclic compounds, although none has yet been reported. 

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