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Valence-bond isomerisations

Benzyne reacts with benzene to give a mixture of products in low yield. The original experiments 38> showed that the 1,4-cyclo-adduct (benzo-barrelene) (19), the valence-bond isomerised 1,2-cyclo-adduct (benzo-cyclo-octatetraene) (20), and the product of insertion into a carbon-hydrogen bond (biphenyl) (21), were obtained in 2,8, and 6% yields respectively. [Pg.42]

Other general principles applicable to the synthesis of heterocycles refer to cycloreversions (either pericyclic and cheletropic or 1,3-dipolar), valence-bond isomerisations and retro-annulations leading to enamines. [Pg.176]

Among the valence-bond isomerisations leading to heterocyclic systems, the synthesis of derivatives of azepine (22) and oxepin (28) have been specially successful (Scheme 6.13) [32]. [Pg.178]

A number of iron-cobalt mixed metal cluster compounds have been obtained by sequential addition of [Co2(CO)g] and [Fe2(CO)g] to [Cp Fe (C0)2-C = C-C=C-H] (77) (Scheme 24). Their formation involves addition of a metal fragment to the C = C bonds, reorganisation of the cluster framework, transfer of metal fragments, valence isomerisation of the C4(H) linkage and 1,2-H shift of the C4H ligand. [Pg.216]


See other pages where Valence-bond isomerisations is mentioned: [Pg.56]    [Pg.57]    [Pg.74]    [Pg.60]    [Pg.56]    [Pg.32]    [Pg.128]    [Pg.37]    [Pg.173]    [Pg.164]    [Pg.404]   
See also in sourсe #XX -- [ Pg.176 , Pg.178 ]




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Bonding isomerisation

Isomerisations

Valence isomerisations

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