Roupany, A;
(2013)
Novel [2+2] Photocycloadditions of Vinylogous Amides and Imides.
Doctoral thesis , UCL (University College London).
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Abstract
This thesis describes investigations into the [2+2] photocycloaddition reaction of vinylogous amides and imides contained within five membered rings with alkenes; the aim of this being the synthesis of aminocyclobutanes. The initial focus is towards intramolecular reactions, synthesising vinylogous amides with a tethered alkene. Irradiation of these compounds leads to a [2+2] photocycloaddition followed by a spontaneous retro-Mannich fragmentation, affording keto-imines. Upon addition of a Boc group to these vinylogous amides, and irradiation of the resultant vinylogous imides, the retro-Mannich fragmentation is prevented and aminocyclobutanes are isolable. Attention is then turned to the intermolecular [2+2] photocycloaddition reaction which does not occur at all with vinylogous amides. However, upon adding an acetyl or Boc group to the vinylogous amides, the intermolecular reaction does take place with certain alkenes. This reaction affords aminocyclobutanes, often as a mixture of regio- and diastereo-isomers. Removal of the Boc group again leads to the retro-Mannich fragmentation taking place. The resultant imine is hydrolysed under the reaction conditions, and 1,5-diketones are obtained in an analogous manner to the de Mayo reaction. If the alkene used in the irradiation has a leaving group connected to the double bond, then this is eliminated after the retro-Mannich fragmentation. In this case, the products are novel conjugated enaminones. The chemistry of these compounds is then investigated. They undergo a Diels-Alder reaction with maleimide and are transformed into aminotropones upon heating or via a bromination-elimination reaction.
| Type: | Thesis (Doctoral) |
|---|---|
| Title: | Novel [2+2] Photocycloadditions of Vinylogous Amides and Imides |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Third party copyright material has been removed from ethesis. |
| UCL classification: | UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1414225 |
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