No / 4-Chloro-2(H)-pyran-2-one undergoes thermal DielsāAlder cycloaddition with electron-deficient dienophiles to afford, without any significant selectivity, 6-endo- and 5-endo-substituted bicyclic lactone cycloadducts. In contrast to 3- and 5-bromo-2(H)-pyran-2-one, 4-chloro-2(H)-pyran-2-one does not undergo thermal cycloadditions with electron-rich dienophiles. The regio- and stereochemical preferences of the cycloadditions of 4-chloro-2(H)-pyran-2-one and other related 2(H)-pyran-2-ones are investigated computationally. Calculations were carried out on the transition states leading to the four possible regio- and stereoisomeric cycloadducts using density functional theory (B3LYP/6-31G*). These studies allow prediction of the regio- and stereoselectivity in these reactions which are in line with experimental observations.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/2366 |
| Date | January 2003 |
| Creators | Afarinkia, Kamyar, Bearpark, M.J., Ndibwami, A. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, No full-text in the repository |
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