Heaney, Frances and O'Mahony, Colm (1998) The influence of oxime stereochemistry in the generation of nitrones from ω-alkenyloximes by cyclization or 1,2-prototropy. Journal of the Chemical Society, Perkin Transactions 1, 1998 (2). pp. 341-350. ISSN 0300-922X

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Abstract

Thermally induced cyclization of the anti-alkenyl oximes E-7a,b and E-17a,b affords cyclic α-alkoxycarbonylnitrones 8 and the 6,7-bicyclic nitrones 18, respectively. The syn-oximes Z-7b and Z-17b react via an alternate pathway to give exclusively the fused isoxazolidine derivatives 10b and 19b, respectively. These oximes are configurationally stable at high temperatures with the energy barrier to isomerization being significantly greater than that to cyclization/cycloaddition. Neither the tert-butyl derivative 7c nor the ε-alkenyl oxime 7d share this characteristic and in these cases the products of thermal activation are independent of the geometry of the starting oxime. For 7c the energy barriers to oxime rotation and cyclization or cycloaddition are sufficiently close to allow all three reactions to proceed. With 7d, cis–trans isomerization and cyclization are the only observed reactions.

Item Type:	Article
Keywords:	oxime stereochemistry; generation; nitrones; ω-alkenyloximes; cyclization; 1,2-prototropy;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	7964
Identification Number:	https://doi.org/10.1039/A704315E
Depositing User:	Dr. Frances Heaney
Date Deposited:	24 Feb 2017 16:33
Journal or Publication Title:	Journal of the Chemical Society, Perkin Transactions 1
Publisher:	Royal Society of Chemistry
Refereed:	Yes
URI:	http://pubs.rsc.org
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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