Publication details
Reversal of Stereoselectivity in Cycloadditions of Five-Membered Cyclic Nitrones Derived from Hexoses
| Authors | |
|---|---|
| Year of publication | 2017 |
| Type | Article in Periodical |
| Magazine / Source | European Journal of Organic Chemistry |
| MU Faculty or unit | |
| Citation | |
| Web | https://onlinelibrary.wiley.com/doi/epdf/10.1002/ejoc.201601488 |
| Doi | http://dx.doi.org/10.1002/ejoc.201601488 |
| Keywords | Heterocycles; Nitrones; Carbohydrates; Cycloaddition; Diastereoselectivity |
| Description | Two five-membered cyclic nitrones derived from hexoses, a newly synthesized D-allo-configured nitrone and an already known D-talo-configured nitrone, have been examined in 1,3-dipolar cycloaddition reactions with vinyl acetate, allyl benzoate, methyl acrylate, acrylonitrile, and vinylene carbonate. The reactions of the D-allo-configured nitrone proceeded preferentially through the expected exo-anti transition state, but all the cycloadditions of the D-talo-configured nitrone surprisingly showed high exo-syn selectivity. This reversal of stereoselectivity has been explained by 3D analysis of the preferred conformations of the nitrones, obtained from X-ray data. The structures were further inspected using CONFLEX, PM5, and DFT calculations. All these methods revealed that the dioxolane substituents attached to C-5 of both nitrones had opposite spatial locations. |
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