Base-catalysed prototropic rearrangement. Part I. Comparison of the base-catalysed and the metal carbonyl-catalysed isomerisation of allyl ethers
- 1 January 1972
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 4,p. 366-370
- https://doi.org/10.1039/p29720000366
Abstract
The light-induced isomerisation of allylic ethers in the presence of pentacarbonyliron has been compared with that brought about by a basic heterogeneous catalyst, KNH2–Al2O3. The reaction on the basic catalyst proceeds through the usual cis-mechanism. In contrast, the carbonyliron reaction gives cis- and trans-isomers, in a 1 : 1 ratio in the case of allyl phenyl ether. A π-complex was detected (by n.m.r. spectroscopy) as an intermediate in the reaction. The formation of a catalyst which was particularly active for the thermal isomerisation of olefinic double bonds was detected during the irradiation of pentacarbonyliron in allyl phenyl ether. 3-Propoxycyclohexene was readily isomerised under these conditions, whereas it remained unchanged in the presence of very strong bases. Conformational effects of the ring were observed.Keywords
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