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Title: Novel [2+2] photocycloadditions of vinylogous amides and imides
Author: Roupany, A.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available