Modification of Photochemical Reactivity by Cyclodextrin Complexation: Selectivity in Photo-Claisen Rearrangement

Syamala, MS and Ramamurthy, V (1988) Modification of Photochemical Reactivity by Cyclodextrin Complexation: Selectivity in Photo-Claisen Rearrangement. In: Tetrahedron, 44 (23). pp. 7223-7233.

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Abstract

Photorearrangements of meta-alkoxyphenylallyl ethers l-5 in ethanol, in water and as complexes of \alpha and \beta cyclodextrins have been investigated. The ratio of the two ortho rearrangement products was dependent both on the length of the alkoxy substituent and on that of the host cavity suggesting that, subtle and rationale engineering manipulation is required to achieve exclusive obtention of only one ortho isomer. It is speculated that \alpha-cyclodextrin provides a “tight fit” while \beta-cyclodextrin offers a “loose fit”. This tightness of binding is suggested to be responsible for the selectivity among the ortho isomers with \alpha-cyclodextrin as the host. Further, the results indicate that “loose cavity" can be tightened by incorporating a “molecular spacer” such as a long hydrocarbon chain as an intramolecular appendix.

Item Type:	Journal Article
Publication:	Tetrahedron
Publisher:	Elsevier Ltd
Additional Information:	Copyright of this article belongs to Elsevier Ltd.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	07 Feb 2008
Last Modified:	19 Sep 2010 04:42
URI:	http://eprints.iisc.ac.in/id/eprint/12986

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