Cycloheptatriene and tropylium metal complexes. Part IX. [1,5] Hydrogen migrations in cycloheptatrienes complexed to chromium
- 1 January 1972
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 9,p. 1141-1144
- https://doi.org/10.1039/p29720001141
Abstract
Specific migration of the ϕ-equatorial 7-endo-hydrogen atom in tricarbonylchromium complexed cycloheptatrienes has been confirmed using the 7-exo- and -endo-phenyl derivatives and the approximate rates of migration have been determined for the 7-exo-methyl and -p-tolyl complexes. In all cases sequential [1,5] migration is shown to occur giving first the 3-, then 1-, and finally 2-substituted products. In the 7-methyl case the energy of activation for rearrangement is considerably lower in the complex than in the free ligand, but the difference is much smaller in the case of aryl substituents. These findings are discussed in relation to a possible mechanism for the rearrangement reaction of the complexes.Keywords
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