Of 1.3,5-cycloheptatriene

On the other hand, the anodic oxidation of 1,3,5-cycloheptatrienes is one of the most powerful key tools for the preparation of a variety of non-benzenoid aromatic compounds such as tropylium salts, tropones, tropolones, 2H -cyclohcpta h furan-2-oncs and azulenes14. 

Formation of dihydrotropylium ions is a key feature of the C H9+ hypersurface. Currently, efforts in our laboratory276 have concentrated on the presence of different C H9+ isomers by probing their bimolecular reactivity. Thus, gas-phase titration in the FT-ICR mass spectrometer has revealed that mixtures of C7H9+ ions are formed by protonation of 1,3,5-cycloheptatriene, 6-methylfulvene and norbomadiene as the neutral precursors but that, in contrast to the results obtained by CS mass spectrometry, fragmentation of the radical cations of limonene yields almost exclusively toluenium ions275. 

Excellent selectivity was observed in the silylation of 1,3,5-cycloheptatriene giving 2-(trimethylsilyl)-l,3,5-cycloheptatriene as the sole product 244... 

Tropolone itself can be prepared in a number of ways, the most convenient of which involves oxidation of 1,3,5-cycloheptatriene with alkaline potassium permanganate. The yield is low but the product is isolated readily as the cupric salt ... 

Exercise 27-13 The esr spectrum shown in Figure 27-18 is a first-derivative curve of the absorption of a radical produced by x irradiation of 1,3,5-cycloheptatriene present as an impurity in crystals of naphthalene. Sketch this spectrum as it would look as an absorption spectrum and show the structure of the radical to which it corresponds. Show how at least one isomeric structure for the radical can be eliminated by the observed character of the spectrum. 

Figure 27-18 Electron-spin resonance spectrum of cycloheptatrienyl radical produced by x irradiation of 1,3,5-cycloheptatriene. See Exercise 27-13.

Photo-oxygenation of 1,3,5-cycloheptatrienes 39 which can undergo valence tautomerization to norcaradiene isomers, leads to the bicyclic endoperoxides 40 and/or tricyclic derivatives 41 depending on the steric and electronic nature of the substituents (Sch. 21) [33]. 

As another example, the electrocyclic interconversion of 1,3,5-cycloheptatriene and norcaradiene also occurs by a disrotatory motion ... 

The reaction of 1,3,5-cycloheptatriene with CsHsCrCla in the presence of iso-C3H7MgBr under UV irradiation, followed by treatment with methanol, yields the brown, paramagnetic (/Xeff=1.63 B.M.), air-sensitive complex, (l,3,5-cycloheptatriene)(cyclopentadienyl)chrom-ium (19) (207). The complex is readily dehydrogenated with platinum to C7H7Cr(C5H5) or oxidized with oxygen in acetone-water to yield the... 

The reaction of 1,3-cyclohexadiene with FeCls in an ether solution of iso-C3H7MgBr produces the complex with mixed ligands (l,3-C,jHn Fe-(CflH(,) (204). Similarly by irradiation of FeClg with a mixture of 1,3,5-cycloheptatriene and 1,3-cycloheptadiene in the presence of iso-CsH7MgBr, Fischer and Muller (206) have prepared the air-sensitive and thermally unstable complex with mixed ligands (1,3,5-C7Hh)(1,3-C7Hio)Fe. Fe(CO)5 reacts with cycloheptatriene to produce not only... 

An important case is the oxidation of alkenes or alkyl arenes containing at least one hydrogen in an a-position [70-77]. The reaction sequence that leads to a-substitution [Eq. (29)] for alkylbenzenes and -naphthalenes most likely includes Eqs. (1), (3), (7), and (11), whereas for alkylanthracenes there is evidence that substitution may take place as an addition-elimination process (see Sec. IV for details). Typical examples are the oxidation of cyclohexene to 3-acetylcyclohexene in AcOH [Eq. (30)] [76], the oxidation of 1,3,5-cycloheptatriene to 7-methoxy-l,3,5-cycloheptatriene in MeOH [74], and the two-... 

B. Deprotonation of 1,3,5-Cycloheptatriene cyclo-C7H7 and the Benzyl Anion... 

PROBLEM 11.2 The heats of hydrogenation of cycloheptene and 1,3,5-cyclo-heptatriene are 110 kJ/mol (26.3 kcal/mol) and 305 Id/mol (73.0 kcal/mol), respectively. In both cases cycloheptane Is the product. What is the resonance energy of 1,3,5-cycloheptatriene How does it compare with the resonance energy of benzene ... 

Table 1.7 C—H bond insertion of 1,3,5-cycloheptatriene reported by Davies.

PROBLEM 13.41 As early as 1891 the German chemist G. Merling showed that the bromination of 1,3,5-cycloheptatriene leads to a liquid dibromide. When the dibromide is heated,... 

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